Answer:
The radioactive element will be left at 2 p.m. will be 0.25 g.
Explanation:
Half life of the radioactive element =[tex]t_{\frac{1}{2}}=1 hour[/tex]
Initial concentration of the radioactive element = [tex]N_o[/tex]=1.0 g
Time elapsed = 12:00 pm to 2:00 pm = 2 hours
Concentration of radioactive element left = N
[tex]\lambda =\frac{0.693}{t_{\frac{1}{2}}}=\frac{0.693}{1 hr}=0.693 hr^{-1}[/tex]
[tex]\log N=\log N_o-\frac{\lambda t}{2.303}[/tex]
Putting the given values in the above equation we get:
N = 0.25 gram
The radioactive element will be left at 2 p.m. will be 0.25 g.
When converting from kilometers to meters, the decimal is moved _______. a. three places to the left b. two places to the left c. three places to the right d. two places to the right.
Answer : The correct option is, (c) three places to the right
Explanation :
The conversion used is:
[tex]1km=1000m[/tex]
For example :
The conversion of 3.1 km into m.
As, [tex]1km=1000m[/tex]
So, [tex]3.1km=\frac{3.1km}{1km}\times 1000m=3100m[/tex]
From this we conclude that, when we are converting from kilometers to meters then decimal is moved three places to the right.
Hence, the correct option is, (c) three places to the right
Which hydrocarbon will provide more heat when allowed to react with oxygen? Hint: Use the heat of combustion data in the alkane properties table. C6H14 C6H12 C2H6 C3H8
Answer:
C6H14
Explanation:
Odyssey ware
Use complete sentences to explain how you determined the mass of oxygen in the compound produced in the virtual lab, and how the mass of each element can be used to determine the empirical formula of the compound.
Answer : To determine the mass of oxygen in the compound produced in the virtual lab, it should be weighed and subtracted from the total weight of the compound. The mass pf each element can be used to determine the empirical formula of the compound by finding out the molar ratios of the individual elements present in the compound. Molar ratios can be obtained by dividing elements by atomic masses of individual elements.
One has to spot the smallest moles of the elements present in the compound and then it has to be divided by rest of the elements in the compound to find the empirical formula of that compound.
Compare the physical and chemical properties of salt and sugar. what properties do they share?
when the volume of a gas is changed from 3.75 L to 6.52 L the temperature will change from 100k to blank k
Hello!
We have an isobaric transformation, that is, when a certain mass under pressure maintains its constant pressure, on the other hand, as we increase the temperature, the volume increases and if we lower the temperature, the volume decreases and vice versa .
We have the following data:
V1 (initial volume) = 3.75 L
V2 (final volume) = 6.52 L
T1 (initial temperature) = 100 K
T2 (final temperature) =? (in Kelvin)
We apply the data to the formula of isobaric transformation (Gay-Lussac), let us see:
[tex]\dfrac{V_1}{T_1} =\dfrac{V_2}{T_2}[/tex]
[tex]\dfrac{3.75}{100} =\dfrac{6.52}{T_2}[/tex]
[tex]3.75*T_2 = 100*6.52[/tex]
[tex]3.75\:T_2 = 652[/tex]
[tex]T_2 = \dfrac{652}{3.75}[/tex]
[tex]\boxed{\boxed{T_2 \approx 173.87\:K}}\Longleftarrow(final\:temperature)\end{array}}\qquad\checkmark[/tex]
_________________________
I Hope this helps, greetings ... Dexteright02! =)
the graph below shows how solubility changes with temperature
Answer:
Option C) Na2SO4 and Na2HAsO4
Explanation:
The solubility of salts can be affected by many things (pH, temperature, etc), this is why when comparing the solubility of two or more salts it's important to establish the conditions.
In this case the graph was made for changes in Temperature, so the first thing is to identify the T=40°C and then, which curves cross at that point.
As can be seen, the red curve (Na2HAsO4) and the blue curve (Na2SO4 ) cross at 40°C indicating that those compounds have similar solubilities at that temperature.
A normal concentration of glucose, or sugar, in the blood is 95 mg/dl. how many grams of sugar would be present per liter of blood? show the conversion factors you use.
What is the overall fusion reaction that converts mass into other forms of energy in the sunâs core? what is the overall fusion reaction that converts mass into other forms of energy in the sunâs core? 3 helium nuclei become 1 carbon nucleus e = mc2 4 hydrogen nuclei become 1 helium nucleus 2 hydrogen nuclei become 1 helium nucleus?
The fusion reaction in the sun's core that converts mass into other forms of energy is known as the proton-proton chain reaction. This process involves the combination of four hydrogen nuclei to form one helium nucleus and the difference in mass is released as energy according to Einstein's equation E=mc^2.
Explanation:The overall fusion reaction that converts mass into energy in the core of the sun is known as nuclear fusion, specifically a process called the proton-proton chain reaction. This is a series of nuclear reactions which results in the combination of four hydrogen nuclei (protons) to form one helium nucleus, with the release of two positrons, two neutrinos (usually called solar neutrinos), and six photons. This is represented by the following reaction:
4H -> He + 2e+ + 2v + 6γ
The mass of the four hydrogen atoms is greater than that of the helium atom produced and, according to Einstein’s equation E=mc^2, the difference in mass is released as energy. The released energy powers the sun and produces the sunlight that we see.
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The sun's energy is generated from a complex process of nuclear fusion, called the proton-proton chain, where four hydrogen nuclei are transformed into a helium nucleus, releasing a significant amount of energy as per Einstein's equation E=mc².
Explanation:The overall nuclear fusion reaction that occurs in the sun involves the conversion of hydrogen nuclei (protons) into helium. This begins when high temperatures within the sun's core cause two protons to combine, forming a deuterium nucleus, an isotope of hydrogen with one proton and one neutron. Further, through a process called the proton-proton chain, more reactions occur which lead to the transformation of four hydrogen nuclei into one helium nucleus, releasing significant energy in the process.
Throughout this process, due to the conversion of mass into energy as postulated by Einstein's equation, E=mc², a tremendous amount of energy is released. Energy in fusion reactions is released in forms such as light (photons), neutrinos, and other particles. This overall process of fusion is the principal source of energy in the sun.
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Joey was taking a chemistry test. one question asked him to write the electron configuration for polonium (po). he wrote it out like this: 1s22s22p63s23p64s23d104p65s24d105p66s25d106p4. joey’s teacher marked it wrong. why?
Polonium has an atomic number of 84 in the periodic table and is solid at 20 degrees Celsius. It is an alpha emitter which is used to extract a thin film for stainless steel. They are used for antistatic devices and a good source of heat for space machines. The correct electron configuration of a polonium atom is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p4. What is lacking in his configuration is the presence of the f sub shell. He should have added 4f14 before 5d10 because if he did not add it, it would give another element.
The pharmacy stocks a 90% w/v solution of drug 'w'. you need to prepare 200ml of a 5mg/ml solution for a patient. what volume of the stock solution will you need?
How does the solubility of a gas change with decreasing temperature?
How many liters of hydrogen gas are needed to react with CS2 to produce 6.5 L of CH4 at STP
Write the net chemical equation for the production of aluminum from aluminum hydroxide and carbon. be sure your equation is balanced.
To produce aluminum from aluminum hydroxide and carbon, the balanced chemical equation is: 2 Al(OH)₃(s) + 3 C(s) → 2 Al(s) + 3 CO(g) + 3 H₂O(g). This ensures all elements are balanced.
To write the net chemical equation for the production of aluminum from aluminum hydroxide and carbon, we must consider the typical reaction: Al(OH)₃(s) + C(s) → Al(s) + CO(g) + H₂O(g)
First, note the elements involved: Aluminum (Al), Carbon (C), Oxygen (O), and Hydrogen (H). We start with the unbalanced equation: 2 Al(OH)₃(s) + 3 C(s) → 2 Al(s) + 3 CO(g) + 3 H₂O(g)Now let’s balance it:
There are 2 Al atoms on both sides.There are 6 O atoms on the left (from 2 Al(OH)₃) and 6 on the right (3 CO and 3 H₂O).There are 6 H atoms on the left (in 2 Al(OH)₃) and 6 H atoms on the right (in 3 H₂O).There are 3 C atoms on both sides.Therefore, the balanced equation is: 2 Al(OH)₃(s) + 3 C(s) → 2 Al(s) + 3 CO(g) + 3 H₂O(g)
What does oxidation mean? what does reduction mean? which of them is endergonic and which is exergonic?
Answer:
1. Oxidation is when a molecule, atom or ion losses an Electron. 2. Reduction is when a molecule, atom or ion gains an electron. 3. endergonic means absorbing energy in the form of work whereas Exergonic means releasing energy in the form of work.
Explanation:
Calculate the dipole moment for hf (bond length 0.917 å), assuming that the bond is completely ionic.
The dipole moment of HF can be calculated through the charge of an electron and bond length. Upon conversion into Debye, it's found to be approximately 4.4 D assuming the HF bond to be completely ionic.
Explanation:The dipole moment of a molecule depends on the difference in electronegativity between the atoms and the distance between the atoms' nuclei. In the case of HF (Hydrogen Fluoride), assuming the bond is completely ionic, we can calculate the dipole moment using the charge of an electron (1.60218 × 10-¹⁹ C) and the bond length (converted to meters).
The bond length of HF given is 0.917 angstroms, which is equivalent to 0.917 x 10-10m or 9.17 x 10-11m. This allows us to calculate the dipole moment in coulomb-meters (C.m) as (1.60218 × 10-¹⁹ C) * (9.17 x 10⁻¹¹m) = 14.69 x 10⁻³⁰ Cm.
We usually express dipole moments in Debyes. To convert C.m to Debye, we use the conversion factor where 1 Debye (D) = 3.336 x 10⁻³⁰ C.m, which gives us a dipole moment of approximately 4.4 D for HF.
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A bug travels at the rate of 3.0 miles per hour. How fast is this in um/nsec? Hint: 2.54cm = 1 inch and 1 mile = 5,280 feet
You are a stem cell therapist who is researching a stem cell therapy to help broken bones heal faster. This therapy involves injecting stem cells into broken bones. Which type of cells would you likely be injecting?
Answer: Osteoblasts!
Explanation:
They form bone.
What is the name of the compound PbS2 • 4H2O?
Final answer:
There seems to be a mix-up as PbS2 • 4H2O doesn't correspond to an accurate chemical compound in this context. Instead, the focus is on the formation of lead sulfate (PbSO4) from reactions involving lead dioxide (PbO2) and sulfur dioxide (SO2) in an acidic medium.
Explanation:
The question seems to be a bit confused in its specifics since PbS2 • 4H2O is not a correctly formulated chemical compound in relation to common lead compounds. However, referring to the provided reactions and information, it seems the question might revolve around lead sulfate (PbSO4) and its reactions. When lead dioxide (PbO2) reacts with sulfur dioxide (SO2) and hydrogen ions in solution, lead sulfate (PbSO4) is formed along with water. This can be seen in the first provided reaction which is essentially about the conversion of lead compounds in acidic medium.
There seems to be a misunderstanding or typo in the compound mentioned, as PbS2 • 4H2O doesn't align with the reactions and compounds discussed, which focus on lead sulfate and its formation. Chemistry often requires precise formulation to accurately represent compounds and reactions.
The reactions provided illustrate the importance of proper chemical notation and understanding chemical compounds involved in electrochemical reactions, like those in lead-acid batteries.
A cart is pulled by a force of 250 N at an angle of 35° above the horizontal. The cart accelerates at 1.4 m/s2. The free-body diagram shows the forces acting on the cart.
The mass of the cart, to the nearest whole number, is kg?
Answer : The mass of the cart is, 146 Kg.
Solution : Given,
Force = 250 N
Angle = [tex]35^o[/tex]
Acceleration = [tex]1.4m/s^2[/tex]
Formula used :
[tex]F\times \cos \theta=m\times a[/tex]
where,
F = force
[tex]\theta[/tex] = angle
a = acceleration
m = mass of the cart
Now put all the values in the above formula, we get the mass of the cart.
[tex]250N\times \cos (35^o)=m\times (1.4m/s^2)[/tex]
[tex]m=146Kg[/tex]
Therefore, the mass of the cart is, 146 Kg.
If you are given an unknown liquid that is 1.0 L and has the mass of 500 grams which of the substance would it be. Distilled Water Density= 1.0g/cm^3, Propane density 0.494 g/cm^3, Salt Water density 1.025 g/cm^3 or Liquid Gold 17.31 g/cm^3?
The unknown liquid is most likely Propane.
To determine the identity of the unknown liquid, we calculate its density and compare it to the densities of known substances. Density is defined as mass divided by volume. Given that the mass of the unknown liquid is 500 grams and the volume is 1.0 L (which is equivalent to 1000 cm3), we use the formula:
Density = Mass / Volume
This gives us:
Density = 500 g / 1000 cm3 = 0.5 g/cm3
Comparing this value to the given options:
Distilled Water Density = 1.0 g/cm3
Propane Density = 0.494 g/cm3
Salt Water Density = 1.025 g/cm3
Liquid Gold Density = 17.31 g/cm3
The density of the unknown liquid (0.5 g/cm3) is closest to that of Propane (0.494 g/cm3), so the unknown liquid is most likely Propane.
Where are electrons in an atom located? moving outside the nucleus inside the nucleus attached to neutrons
What property do all of the group 18 elements have that make them stand out from other elements?
The bond formed between iron (electronegativity = 1.9) and chlorine (electronegativity = 3.2) is
Answer:
Polar covalent.
Explanation:
Hello,
In this case, ionic and covalent bonds could be differentiated by subtracting the constituents' electronegativities. Thus, for iron and chlorine, we have:
[tex]\Delta E=E_{Cl}-E_{Fe}=3.2-1.9=1.3[/tex]
Hence, when such difference is less than 1.7, the bond is polar covalent as it is also greater than 0.7.
Best regards.
The number of particles in 1 mole of hydrogen gas is ________.
The ph of a 0.55 m aqueous solution of hypobromous acid, hbro, at 25.0°c is 4.48. what is the value of ka for hbro?
Answer:
The value of dissociation constant for the hypobromous acid is [tex]1.993\times 10^{-9}[/tex].
Explanation:
The pH of the solution = 4.48
Concentration of hypobromous acid,[tex][HBrO]=c=0.55 M[/tex]
The equilibrium reaction for dissociation of HBrO (weak acid) is,
[tex]HBrO\rightleftharpoons OBr^-+H^+[/tex]
initially conc. c 0 0
At eqm. [tex]c(1-\alpha )[/tex] [tex]c\alpha [/tex] [tex]c\alpha [/tex]
First we have to calculate the concentration of value of degree of dissociation [tex]\alpha [/tex].
Expression for dissociation constant is given as:
[tex]k_a=\frac{(c\alpha )(c\alpha )}{c(1-\alpha )}=\frac{c(\alpha )^2}{(1-\alpha )}[/tex]..(1)
[tex][H^+]=c\alpha [/tex]
[tex]pH=4.48=-\log[H^+]=-\log[c\alpha ]=-\log[0.55 M\times \alpha ][/tex]
[tex]\alpha =6.0205\times 10^{-5}[/tex]
Substituting all the values in (1), we get the value of dissociation constant:
[tex]K_a=\frac{0.55 M(6.0205\times 10^{-5})^2}{(1-(6.0205\times 10^{-5}))}[/tex]
[tex]K_a=1.993\times 10^{-9}[/tex]
The value of dissociation constant for the hypobromous acid is [tex]1.993\times 10^{-9}[/tex].
A 0.55 M aqueous solution of HBrO has a pH of 4.48. The value of Ka for HBrO is 1.99 × 10⁻⁹.
HBrO is a weak acid according to the following equation.
HBrO ⇄ H⁺ + BrO⁻
Given the pH is 4.48, the concentration of H⁺ is:
[tex]pH = -log [H^{+} ]\\[H^{+} ] = antilog-pH = antilog-4.48 = 3.31 \times 10^{-5} M[/tex]
Given the initial concentration of the acid (Ca) is 0.55 M, we can calculate the acid dissociation constant (Ka) using the following expression.
[tex]Ka = \frac{[H^{+}]^{2} }{Ca} = \frac{(3.31 \times 10^{-5} )^{2} }{0.55} = 1.99 \times 10^{-9}[/tex]
A 0.55 M aqueous solution of HBrO has a pH of 4.48. The value of Ka for HBrO is 1.99 × 10⁻⁹.
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Which of the following conditions increases the frequency of collisions without changing the energy or concentration of reactants?
A: increasing the surface area of the substance
B: adding more reactant molecules
C: increasing the temperature
D: increasing the pressure
Answer:
A: increasing the surface area of the substance
Explanation:
What are the two parts of an atom?
Answer:
The nucleus and the electron cloud.
Explanation:
The protons and neutrons are in the nucleus and the electrons and in the electron cloud. Hope this helps!
How test berween nitric and sulferic acid?
Which orbital would the electron of a ground state hydrogen atom occupy? 1s 1p 2p none of the above 0s?
In the ground state, a hydrogen atom's electron occupies the 1s orbital, which is the lowest energy state and has a spherically symmetrical probability distribution.
The electron of a ground state hydrogen atom would occupy the 1s orbital. The ground state refers to the lowest energy state available to an electron in an atom.
In hydrogen's case, this is the 1s state, which has n = 1 (the principal quantum number indicating the energy level) and l= 0 (the orbital angular momentum quantum number, which for s orbitals is always zero).
This state is also spherically symmetrical, meaning the electron probability distribution around the nucleus is even in all directions.
Furthermore, the energy order of orbitals shows that 1s is lower than 2s, 2p, 3s, etc., indicating that electrons fill the 1s orbital before any others when in the ground state.
If an isotope of an element has 18 neutrons and a mass number of 35, how many electrons must it have?