Answer:
the only element above is potassium
1) Give a detailed explanation of how you can use the laboratory technique of titration to determine the concentration of an acetic acid solution.
2) When a reaction is reversible, eventually the rates of the forward and reverse actions will be equal. Which of the following best explains what this means?
The concentrations of the reactants and products have become equal.
The concentrations of the reactants have become constant.
The concentrations of the reactants have not reacted well.
The concentrations of the reactants have completed their reaction.
3) Balance the following redox equation and identify the element oxidized, the element reduced, the oxidizing agent, and the reducing agent. Show all of the work used to solve the problem. (5 points)
NO2- + Al yields AlO2- + NH3
1) Answer is: Determine the endpoint of titration.
The endpoint is the point at which the indicator changes colour in a colourimetric titration and that is point when titration must stop.
Equivalence point is the point which there is stoichiometrically equivalent amounts of acid and base.
Chemist can draw pH curve (graph showing the change in pH of a solution, which is being titrated) for titration and determine equivalence point.
This is example of acid-base titration.
a) measure volume and molarity of some strong base, for example sodim hydroxide (NaOH).
b) measure the volume of acetic acid into a beaker.
c) titrate until the endpoint is reached, when the colour of indicator, for example phenolphthalein changes color.
d) Use balanced chemical reaction of acetic acid and sodium hydroxide:
CH₃COOH(aq) + NaOH(aq) → CH₃COONa(aq) + H₂O(l). From molarity and volume of base determine the concentration of acetic acid.
2) Answer is: The concentrations of the reactants have become constant.
For example, balanced chemical reaction: 2CH₄(g) ⇄ C₂H₂(g) + 3H₂(g).
a) In a chemical reaction, chemical equilibrium is the state in which both reactants (methane CH₄) and products (ethyne C₂H₂ and hydrogen H₂) are present in concentrations which have no further tendency to change with time.
b) At equilibrium, both the forward and reverse reactions are still occurring.
c) Reaction rates of the forward and backward reactions are equal and there are no changes in the concentrations of the reactants and products.
3) Chemical equation: NO₂⁻ + Al → AlO₂⁻ + NH₃.
Oxidation half reaction: Al⁰ + 4OH⁻ → AlO₂⁻ + 2H₂O + 3e⁻ /×2.
Reduction half reaction: NO₂⁻ + 5H₂O + 6e⁻ → NH₃ + 7OH⁻.
Oxidation half reaction: 2Al⁰ + 8OH⁻ → 2AlO₂⁻ + 4H₂O + 6e⁻.
Reduction half reaction: NO₂⁻ + 5H₂O + 6e⁻ → NH₃ + 7OH⁻.
Balanced chemical equation:
2Al + 8OH⁻ + NO₂⁻ + 5H₂O → 2AlO₂⁻ + 4H₂O + NH₃ + 7OH⁻.
The same species on opposite sides of the arrow can be canceled:
2Al + OH⁻ + NO₂⁻ + H₂O → 2AlO₂⁻ + NH₃.
Aluminium is oxidized (change oxidation number from 0 to +3) and nitrogen is reduced (change oxidation number from +3 to -3).
Aluminium is reducing agent (lost electrons) and nitrogen is oxidizing agent (gain electrons).
Help. The third and last question are
3 A 2- N force presses down on the marble at the same time as a 1.5N force acts on the right side of the marble
4 A marble rolling downhill suddenly comes to rest at a garden wall
Balanced forces means the forces acting on the object are either equal but in opposite directions or zero.
For the first option, something starting to roll means it has an unbalanced force acting on it.
For the second option, these forces are equal and in opposite directions, so these are balanced forces.
For the third option, the forces are not equal and not in opposite directions, so these are unbalanced forces.
And for the last option, something that changes speed does not have balanced forces.
The questions pertain to the effects of forces on an object (a marble) within the field of physics. The first involves combining two forces acting in different directions, and the second involves Newton's first law of motion.
Explanation:The subject of these questions pertains to force and its effects, specifically in the context of physics. In the first scenario, we're looking at the combination of two forces on an object (the marble). The 2-N force pressing down and 1.5-N force acting to the right will result in a net force at an angle, according to vector addition. In the second scenario, the concept of Newton's first law of motion comes into play. The marble, initially in motion, comes to rest when it hits the garden wall because an external force (the wall) is applied, disrupting its initial state of motion.
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What is the number if electrons in the outermost energy level of an oxygen atom?
2
8
4
6
6 is the number of electrons in the outermost energy level of an oxygen atom.
So the correct answer would be six.
Hope this helps,
Davinia.
Structural formulas are like models because they show _[blank]_.
Which answer best completes this statement?
a condensed way of writing a compound
how elements arrange within a compound
how electrons arrange within a compound
the three-dimensional shape of a compound
The correct option is:
how elements arrange within a compound
Structural formula are like models because they show how elements arrange within a compound.
the reason why iodine sublimes
The intermolecular forces for Iodine are much lower than the energy needed to free it from its crystal lattice. Once Iodine has enough energy to break out of the lattice, it also has enough energy to separate from its neighbors. And so, it sublimes.
What is the volume of 7.25 g of oxygen gas at STP?
Answer:
5.15 L
Step-by-step explanation:
This looks like a case where we can use the Ideal Gas Law to calculate the volume.
pV = nRT Divide both sides by p
V = (nRT)/p
Data:
m = 7.25 g
R = 0.083 14 L·atm·K⁻¹mol⁻¹
T = (0 +273.15) K = 273.15K
p = 1 bar (Note: STP is 1 bar and 0°C)
Calculations:
(a) Moles of O₂
n = m/M
n = 7.25/32.00
n = 0.2266 mol
(b) Volume
V = (0.2266 × 0.083 14 × 273.15)/1
V = 161.3/2.00
V = 5.15 L
The volume of 7.25 g oxygen gas at STP has been 5.075 L.
The oxygen has been assumed to be an ideal gas. The volume of 1 mole of an ideal gas at STP has been 22.4 L.
Volume of Oxygen at STPThe moles of a gas has been given as:
[tex]\rm Moles=\dfrac{Mass}{Molar\;mass}[/tex]
The given mass of oxygen has been 7.25 g.
The molar mass of oxygen has been 32 g.
The moles of oxygen gas have been given as:
[tex]\rm Moles\;O_2=\dfrac{7.25}{32}\\Moles\;O_2= 0.226\;mol[/tex]
The moles of oxygen available has been 0.226 mol.
The volume of 0.226 mole oxygen at STP has been:
[tex]\rm 1\;mol=22.4\;L\\0.226\;mol=0.226\;\times\;22.4\;L\\0.226\;mol=5.075\;L[/tex]
The volume of 7.25 g oxygen gas at STP has been 5.075 L.
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an air sample consists of 99.6% of nitrogen-14 and 0.4% of nitrogen-15. what is the average mass of nitrogen in this sample?
The average mass of nitrogen is 14
calculation
step 1 : multiply each percentage by mass number
14 x 99.6 =1394
15 x 0.4 = 6
Step 2: add them up
1394 + 6 = 1400
step 3: Then divide by 100
= 1400/100 = 14
Answer:The average atomic mass of nitrogen is 14.004
Explanation:
Abundance of nitrogen-14 = 99.6 %
Fractional abundance[tex]=\frac{99.6}{100}=0.996[/tex]
Abundance of nitrogen-15 = 0.4 %
Fractional abundance[tex]=\frac{0.4}{100}=0.004[/tex]
Average atomic mass of an element =
[tex]\sum(\text{atomic mass of an isotopes}\times (\text{fractional abundance}))[/tex]
Average atomic mass of nitrogen =
[tex]14\times 0.996+15\times 0.004amu=14.004[/tex]
The approximate atomic mass of nitrogen is 14.004
2. What is the molarity of 100 mL of a 3.0% H2O2 (mass/volume) solution? What is the molarity of 100 mL of a 2.25% H2O2 solution?
The 3% mass/volume H₂O₂ means 3 g of H₂O₂ in 100 ml of water.
Now, Molarity (M) = No. of moles of H₂O₂ / Volume of solution in liter
No. of moles of H₂O₂ = Mass / Molar mass = 3 g / 34 g/mol = 0.088 mol
So, molarity = 0.088 × 1000 ml / 100 ml = 0.88 M
In case of 2.25 % H₂O₂,
No of moles = 2.25 g / 34 g/mol = 0.066 mol
Molarity = 0.066 mol / 0.100 L = 0.66 M.
The molarity of a 3.0% H₂O₂ solution is 0.88 M, and the molarity of a 2.25% H₂O₂ solution can be calculated using the same steps. The molarity of a solution is determined by dividing the moles of solute by the volume of the solution in liters.
Explanation:The molarity of a solution is represented by the formula:
Molarity (M) = (moles of solute) / (volume of solution in liters)
First, we need to calculate the moles of H₂O₂ in each solution:
For the 3.0% H₂O₂ solution:
Convert the mass of H₂O₂ to grams: 3.0% of 100 mL is 3 grams.Convert grams of H₂O₂ to moles: we need to use the molar mass of H₂O₂, which is 34.0147 g/mol. Therefore, 3 grams / 34.0147 g/mol = 0.088 moles.For the 2.25% H₂O₂ solution:
Follow the same steps as above, using the mass of the solution (2.25% of 100 mL is 2.25 grams) and the molar mass of H₂O₂.Now we can calculate the molarity of each solution:
For the 3.0% H₂O₂ solution: Molarity = 0.088 moles / 0.1 L = 0.88 M.
For the 2.25% H₂O₂ solution: Molarity = (moles of solute) / (volume of solution in liters).
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Please fill out all of table!!
1) Alkali metals - s block; one valence electron; lose one valence electron; charge of an ion +1.
Alkali metals have electronegativity from 0.7 to 1, lowest in Periodic table of elements, which means that alkali metals (I group in Periodic table) has positive oxidation number in compounds.
Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.
For example, sodium (Na) is an element with atomic number 11 and it has one valence electron (3s¹) like all alkaline metals.
Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.
2) Alkaline earth metals - s block; two valence electrons; lose two electrons; charge of an ion is +2.
Beryllium, magnesium,calcium and strontium are alkaline earth metals. The elements have very similar properties. Alkaline earth metals have in common an outer s- electron shell (two electrons).
For example, atomic number of calcium is 20, it means that it has 20 protons and 20 electrons, so atom of calcium is neutral.
Electron configuration of calcium atom: ₂₀Ca 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²; calcium has two valence electrons (4s²).
3) Boron group - p block; three valence electrons; lose three electrons; charge of metal ions is +3; no nonmetals in this group; none.
For example, boron is an element with atomic number 5, which means it has 5 protons and 5 electrons, bcause atom has neutral charge.
Electron configuration of boron: ₅B: 1s² 2s² 2p¹, it has three valence electrons in 2s and 2p orbitals.
Atomic number is the number of protons, which is characteristic of a chemical element.
4) Carbon group - p block; four valence electrons; lose two or four electrons; charge of metal ions is +2 or +4; nonmetals gain four electrons; charge of nonmetals is -4.
Carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) and flerovium (Fl) are in group 14 of Periodic table. They have same number of valence electrons (four) and similar chemical properties.
For example, carbon is a chemical element with symbol C and atomic number 6, which means it has 6 protons and six electrons. Valence electrons are in 2s and 2p orbitals.
Electron configuration of carbon atom: ₆C 1s² 2s² 2p².
5) Nitrogen group - p block; five valence electrons; lose three or five electrons; charge of metal ions is +3 or +5; nonmetals gain three electrons; charge of nonmetals is -3.
Nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and moscovium (Mc) are in group 15 of Periodic table. They have same number of valence electrons (five).
For example, bizmuth (Bi) has atomic number 83, it has 83 protons and 83 electrons. Valence electrons are in 6s and 6p orbitals.
Electron configuration of bizmuth atom: ₈₃Bi [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³.
6) Oxygen group - p block; six valence electrons; lose four or six electrons; charge of metal ions is +4 or +6; nonmetals gain two electrons; charge of nonmetals is -2.
Oxygen (O), sulfur (S), selenium (Se), tellurium (Te) and the radioactive element polonium (Po) are in group 16 of Periodic table. They have same number of valence electrons (six).
For example, electron configuration of oxygen atom: ₈O 1s² 2s² 2p⁴.
Oxygen atom has six valence electrons (2s² 2p⁴), so it is in 16 group of Periodic table of elements.
7) Halogens - p block; seven valence electrons; nonmetals gain one electron; charge of nonmetals is -1.
Halogen elements are in group 17: fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). They are very reactive and easily form many compounds.
Halogens need to gain one electron to have electron cofiguration like next to it noble gas.
For example, fluorine has 9 electrons and it gain easily one electron in chemical reaction to have electron configuration like noble gas neon (Ne) with 10 electrons.
Electron configuration of fluorine: ₉F 1s² 2s² 2p⁵.
8) Noble gases - p block; eight valence electrons (except helium with two valence electrons); do not gain or lose electrons; none.
Noble gases (group 18) are in group 18: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). They have very low chemical reactivity.
Noble gases have very stable electron configuration and does not need to gain electrons, only when they gain energy .
Helium has atomic number 2, it has 2 protons and 2 electrons.
Electron configuration of helium atom: ₂He 1s².
Electron configuration of krypton atom:
₃₆Kr 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶.
A child is male because he has one X chromosome and one Y chromosome where did these chromosomes come from
it would come from your mom and dad
why is the fact that light travels at 300,000 km/s is a consequence of energy conservation?
Light traveling at a constant speed is a consequence of the conservation of energy and is embodied in Einstein's equation E = mc^2. This speed limit contributes to the principles of energy and mass-energy conservation, with implications for relativistic phenomena like time dilation and length contraction.
Explanation:The fact that light travels at 300,000 km/s is a consequence of the conservation of energy. This principle is embodied in Einstein's famous equation E = mc2, where E denotes energy, m denotes mass, and c denotes the speed of light. This equation suggests that mass and energy are interchangeable.
According to the theory of relativity, if an object with mass attempted to reach the speed of light, it would require infinite energy, which is physically impossible. Therefore, the speed of light is a universal speed limit. This limit contributes to the principle of energy conservation and the closely related concept of mass-energy conservation.
Further consequences of the speed of light include time dilation, length contraction, and increased momentum as objects approach this speed. Equivalently, if a mass could reach the speed of light, these effects suggest that it would convert into pure energy, again consistent with E = mc2 and the conservation of mass-energy.
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If you drop a 25-gram piece of metal that has a temperature of 100° Celsius into 1000 grams of water at 20° Celsius, what best describes what would occur?
1. the temperature lost by the metal will equal the temperature gained by the water
2. the heat lost by the metal will equal the heat gained by the water
3. the final temperature will be 60 degrees celsius
4. the final temperature will be more than 60 degrees celsius
Answer is: 2. the heat lost by the metal will equal the heat gained by the water.
1) the temperature lost by the metal will equal the temperature gained by the water is not correct, because temperature is the intensity of heat present in a substance and a thermometer is a device that measures temperature or a temperature gradient.
3) the final temperature will be 60 degrees celsius is not correct, because amount of water is greater than amount of metal, so the the final temperature will be less than 60 degrees celsius.
4) same as 3).
The term “ average atomic mass “ is a ______average so is calculator different Lee from a normal average
Average atomic mass of an element is a sum of the product of the isotope mass and its relative abundance.
For example: Chlorine has 2 isotopes with the following abundances
Cl(35): Atomic mass = 34.9688 amu; Abundance = 75.78%
Cl(37): Atomic mass = 36.9659 amu; Abundance = 24.22 %
Average atomic mass of Cl = 34.9688(0.7578) + 36.9659(0.2422) =
= 26.4993 + 8.9531 = 35.4524 amu
Thus, the term “ average atomic mass “ is a weighted average so it is calculated differently from a normal average
Which rule is used when writing the name of an ionic bass
Answer:
Name = name of metal + hydroxide.
Step-by-step explanation:
You name an ionic base according to the rule:
Name = name of metal + hydroxide
Thus,
NaOH = sodium hydroxide
Ca(OH)₂ = calcium hydroxide
Al(OH)₃ = aluminium hydroxide
Which of the following reactions could be used to power a battery because of the transfer of electrons?
Pb22+ + 2Br− → PbBr
CaCl2 + 2NaOH → Ca(OH)2 + 2NaCl
KOH + HCl → KCl + H2O
Zn + Cu2+ → Zn2+ + Cu
Answer is: Zn + Cu2+ → Zn2+ + Cu.
In this chemical reaction, there is transfer of electrons from zinc (Zn) to copper (Cu). Zinc change oxidation number from 0 to +2 (lost electrons) and copper change oxidation number from +2 to 0 (gain electrons).
Oxidation half reaction: Zn⁰ → Zn²⁺ + 2e⁻.
Reduction half reaction: Cu²⁺ + 2e⁻ → Cu⁰.
In other chemical reactions, there is no change of oxidation number of elements.
Which of the following colors of visible light has the lowest energy?
A) blue
B) green
C) red
D) yellow
Answer:
Its blue
Explanation:
Is Fe2O3+H2--2Fe+3H2O balanced or unbalanced?
hydrogen is not balanced
the right balanced equation is
Fe2O3 + 3 H2 -> 2Fe + 3H2O
Which answer choice provides the best set of tables for wave a and wave b
Answer:
Option D
Wave A: Low Frequency Wave
Wave B: High Frequency Wave
Which of the following is a noncontact force?
A.
magnetic forces
B.
electrical forces
C.
gravitational forces
D.
all of these
How do nonmetals conduct electricity? well . by giving up electrons . poorly . better than metals.
Usually poorly, especially at room temperature for most of them. The gases do not conduct. Some that are marginally non metals (silicon germanium and graphite) conduct passably well but do not conduct as well as copper or silver.
Non metals do not have easily freed electrons and that is why they do not conduct electricity.
Which two factors does the power if a machine depend on
A. work and distance
B. force and distance
C. work and time
D. time and distance
The definition of mechanical power is
Power = (work done) / (time to do the work).
From that definition, it looks pretty much like the power of a machine
depends on work and time.
Answer:
c. work and time
Explanation:
c is right on plato
What is the difference between atomic mass and atomic numbers
Atomic mass (amu) = the number of protons and electrons
Atomic numbers = the little number on the periodic table that any element has which represents the number of protons in the nucleus
Atomic number is the number of protons that are inside that atom. This helps identify which element an atom is.
Atomic mass is the number of protons and neutrons inside an atom.
what is a chemical change?
Chemical change accurs when a substance changes form like liquid to solid.
The requirements of atoms to be able to participate in hydrogen bonding with a hydrogen atom include all of the following except A. atoms must not be able to closely approach the hydrogen. B. atoms must be electronegative. C. atoms must have one lone pair of electrons. D. atoms must be small.
B. atoms must be electro negative.
Answer:
The answer is A.
Explanation:
This is a specific type of polar interaction that is established between two atoms with high electronegativity, usually between O or N, and an atom of H. In the case of oxygen, with a total of 8 electrons, two pairs of solitary electrons are presented and can act as acceptors of two hydrogen bridges. Nitrogen has one less electron and therefore has only one pair of solitary electrons to form a hydrogen bridge. These orbitals have a high negative charge density, and can, therefore, bind to the positive charge of hydrogen.
The interatomic distance between the hydrogen and the acceptor is less than the sum of its Van der Waals radius. The atomic radius of N and O are relatively small.
Have a nice day!
What is the symbol for an isotope of carbon with 7 neutrons?
C-13. 6 protons 7
neutrons.
Using the law of conservation of energy, explain why an LED light is more energy efficient that an incandescent light bulb.
Answer:
An LED light uses one-third the energy of an incandescent bulb to produce the same amount of light.
Step-by-step explanation:
A typical 100 W incandescent bulb produces about 5 % visible light, 83 % IR radiation, and 12 % heat (it is the IR radiation that makes the bulb feel hot).
It produces about 5 J of light energy for every 100 J of energy input.
A typical LED bulb produces about 15 % visible light and 85 % heat (LEDs feel cool, because they don't produce IR radiation).
It produces about 15 J of light energy for every 100 J of energy input.
Thus, an LED light is about three times as efficient at converting electrical energy into light
Final answer:
An LED light is more energy efficient than an incandescent bulb as it converts more electrical energy into light with less waste as heat, making it a cost-effective and environmentally friendly option.
Explanation:
Using the law of conservation of energy, an LED light is more energy efficient than an incandescent light bulb because it converts a higher percentage of electrical energy into light, with minimal energy wasted as heat. Incandescent bulbs, in contrast, waste much of their energy as heat. For example, a 60-W incandescent bulb can be replaced by a 15-W CFL (Compact Fluorescent Light), which has the same brightness and color, demonstrating CFL's higher efficiency. LED lights push this efficiency even further, being twice as efficient as CFLs and lasting five times longer, though initially more costly. The movement towards LED lighting is driven by their ability to reduce power consumption significantly, thus lowering the cost and environmental impact of lighting homes and businesses.
Which equation is NOT balanced? a. 2H2 + O2 → 2H2O c. Fe2O3 + 3H2 → 2Fe + 3H2O b. 4NH3 + 5O2 → 4NO + 6H2O d. 3H2 + 2O2 → 2H3O
option d
the values are wrong on the right hand side of the equation, the right equation is above a,b,c.
The chemical equation that is NOT balanced is option d, which has an unequal number of atoms on the reactant and product sides.
To determine if a chemical equation is balanced, we must check that the number of atoms of each element on the reactant side is equal to the number of atoms of the same element on the product side. Comparing the given equations:
a. 2H₂ + O₂ → 2H₂O: This equation is balanced because there are 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.c. Fe₂O₃ + 3H₂ → 2Fe + 3H₂O: This equation is also balanced, with 2 iron atoms, 3 oxygen atoms, and 6 hydrogen atoms on each side.b. 4NH₃ + 5O₂ → 4NO + 6H₂O: This equation is balanced when we count the nitrogen, oxygen, and hydrogen atoms.d. 3H₂ + 2O₂ → 2H₃O: This equation is NOT balanced because there are 6 hydrogen atoms on the reactant side but 6 hydrogen atoms and an extra oxygen atom on the product side.Thus, option d is the equation that is not balanced.
Which of the following choices demonstrates how the writer creates the point that physical responses to stressful situations is part of human nature? A) The author compares a caveman physically responding to a tiger to a modern man physically responding to an unknown situation at work. B) The author examines the stressful situation people face today and concludes that they are much more stressful than those faced in the past. C) The author stresses that physical reactions to stress are always positive. D) The author explains that cavemen used their physical responses to survive.
D I believe is the correct answer
When hydrochloric acid reacts with potassium hydroxide solution, the following reaction occurs. HCl (aq) + KOH (aq) H2O (l) + KCl (aq) The reaction gives off heat energy, so it is an reaction.
A reaction that gives off heat energy is called Exothermic. (Answer).
A reaction that absorbs heat from the surroundings is called endothermic.
Answer: Exothermic
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and [tex]\Delta H[/tex] for the reaction comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and [tex]\Delta H[/tex] for the reaction comes out to be positive.
[tex]HCl(aq)+NaOH(aq)\rightarrow KCl(aq)+H_2O(aq)[/tex] is an example of neutralization as acid and base combines to form salt and water and exothermic reaction as it releases heat in the reaction.
What does graphite contain that is similar to metals