8. What happens to matter during a chemical reaction​

Cutting of Nails is a physical change since no new substance is formed.

Proper hand hygiene involves careful cleaning and trimming of the nails, which carry dirt and germs and can contribute to the spread of some infections such as helminths. The nails should be short and the underside should be cleaned frequently with soap and water.

For most people, if you don't trim your nails, your nails will be longer at first. “If you don't trim your nails, your nails will continue to grow,” he says. James Christina, Executive Director and CEO of the American Podiatric Medical Association. "It's like the hair on your head."

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Answer:

B. Polling is the most widely used method of formally measuring public opinion.

Answer:

B. Polling

Explanation:

Answer:

by equal number of protons and electrons it balances it out

Due to interaction of proton particle and electron particle, neutrality in atom is achieved.

It is a common known statement that matter is composed of atom, and atom is composed of particles called as electron, neutron, and proton. The atoms are considered as charged particles due to the presence of charges on its composition molecules.

The electrons are negative charged particles whereas the protons are positively charged particles. The number of protons and electron in an atom remains equal. Due to this condition, all the protons react with the entire electron leading to a condition called neutrality.  

Answer: Option (2), (4) and (5)

Explanation:

Absolute zero refers to the temperature from which there occurs no cooling. Scientists have not been able to cool any substance upto its absolute zero temperature. A temperature close to the absolute zero temperature is attained but it never exactly reaches the absolute temperature.

For the conversion from celsius scale to kelvin or from kelvin to celsius scale, it is universally taken to be 0 K= -273°C.

Gas can never be zero volume because gas is a matter and certain composition and thus has its own volume.

In Kelvin scale, k is used whereas in celsius scale, degree (°) is used.

Cryosphere refers to the study of the materials and their characteristics at a relatively very low temperature.

Thus, the correct answers are option (2), (4) and (5).

Answer:

nstead of using two dots to indicate the two electrons that comprise the covalent bond, a line is substituted for the two dots that represent the two electrons. Below is shown the Lewis structure for water. Two hydrogens (H) are separately covalently bonded to the central oxygen (O) atom.

Explanation:

The total number of electrons that are represented by a dash (-) in a Lewis dot structure compound is 2(Two).

So, the total number of electrons that are represented by a dash (-) in a Lewis dot structure compound is 2(Two).

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The oxidizing agent do in a redox reaction is "donates electrons".

A material that obtains electrons and would be reduced, which results in a drop in oxidation state, would be an oxidizing agent. The other substance oxidized to form due to it.

The smallest elemental component of an atom, the electron has a negative charge. In a neutral atom, there are an equal number of protons as well as electrons.

Therefore, the oxidizing agent do in a redox reaction is "donates electrons".

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Answer:

A. Oxidizes another atom

Explanation:

Just did the quiz and guessed B, but got it wrong, and showed me that A is correct.

Answer:

a thing that is composed of two or more separate elements; a mixture.

Explanation:

Answer:

=1.666 liters

Explanation:

1 mole of a has at standard temperature and pressure occupies a volume of 22.4 liters.

0.5 moles of nitrogen occupy a volume of (0.5 moles×22.4 dm³/mol)/ 1

=11.2 liters.

Standard pressure= 1 atmosphere (Atm)

Standard temperature = 273.15 Kelvin

According to Combined gas equation, P₁V₁/T₁=P₂V₂/T₂

Let us take the conditions under standard conditions as the reference, with the subscript 1 and the conditions under the 5L container to be scenario 2 with subscript 2.

Therefore P₂ =P₁V₁T₂/T₁V₂

Substituting for the values we get:

P₂= (1 atm× 11.2L ×203K)/ (273K×5L)

=1.666 atm

Answer:1.35 x 10^24

Explanation:

No. of molecules= mole x avogadro's constant

2.25 x 6.02 x 10^23

=1.35 x 10^23

Answer: The number of molecules in given amount of sulfuric acid is [tex]1.35\times 10^{24}[/tex]

Explanation:

According to the mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules.

We are given:

Moles of sulfuric acid = 2.25 mole

So, the number of molecules that will be present in 2.25 moles of sulfuric acid will be [tex]2.25\times 6.022\times 10^{23}=1.35\times 10^{24}[/tex] number of atoms.

Hence, the number of molecules in given amount of sulfuric acid is [tex]1.35\times 10^{24}[/tex]

Answer:

The correct answer is D: 16.4 g

Explanation:

Look at the balanced equation of NaBr, It has 1:1 between Na and Br.

NaBr ---> Na+ and Br-

If the solution has 0.245 concentration of bromide ions then the solution has 0.245 concentration of sodium ions as well. Which means both have equal concentration. So the molarity of solution is 0.245 M.

Convert volume in dm3.

650ml = 650 cm3  

650cm3/ 1000cm3 x 1dm3 = 0.65 dm3

Mass of a solute (g) = Molarity x Molar mass of solute x volume in dm3

                               = 0.245 M X 102.89 g/mol x 0.65 dm3

                             = 16.38 = 16.4 g

Answer:

The correct answer is D) 16.4.

The mass of sodium bromide in solution is 16.4 g

Further Explanation:

Molarity may be defined as the concentration of a solution in moles per liter. It is calculated by dividing the number of moles of a solution, n by its volume in liters, V. That is; Molarity = n/V

Therefore; when given the molarity of a solution and the volume of the solution then we can get the number of moles, by multiplying the molarity by volume; n = MV.

Additionally, the number of moles of a compound or an element can also be calculated by dividing the mass of the compound by its relative molecular mass.

In this question, we are given;

Molarity of a bromide ion = 0.245 M

But the dissociation of sodium bromide is;

NaBr(aq) → Na+(aq) + Br-(aq)

Therefore, the molarity of NaBr is 0.245 M since the mole ratio of NaBr : Br- is 1: 1.

Hence; Number of moles of NaBr = Molarity × volume

                                                        = 0.245 M × 0.650 L

                                                        = 0.15925 moles

But; number of moles = mass/ molecular mass

Molecular mass of NaBr is 102.894 g/mol

Therefore;

Mass of NaBr = Number of moles × molecular mass

                      = 0.15925 × 102.894 g/mol

                      = 16.385 g

                      ≈ 16.4 g

Thus, the mass of sodium bromide in solution is 16.4 g

Grade: Middle  School

Subject: Chemistry

Chapter: Mole and stoichiometry equations

Keywords: Molarity, moles, sodium bromide, molecular mass and volume.

Answer:

use a calculator please

Answer:

250,000

Explanation:

Answer:

Tk=TC+273.15

so

1376.06=Tc+273.15

TC=1376.06-273.15

TC= =1,102.91

Answer: 1102.91 ºC

Explanation: To solve this problem, we only need to isolate the temperature in Celsius from the given equation:

TK=TºC+273.15

TºC=TK-273.15

now, replacing the temperature of the flame in K:

TºC=1376.06-273.15

TºC=1102.91 ºC

The teacher bought 20 cheaper calculators at $2.95 each after setting up and solving an algebraic equation that includes the total cost spent and the price of 40 more expensive calculators.

First, let's define the variables: Let x be the number of cheaper calculators that the teacher bought.

The problem states that the teacher bought 40 calculators at $8.20 each, so this cost is $8.20 times 40, and the other calculators cost $2.95 each, so this is $2.95 times x. The total cost is given to be $387.

We can set up the equation as follows:

$328 + $2.95x = $387

$2.95x = $387 - $328

$2.95x = $59

[tex]x = \frac{\$59}{\$2.95}[/tex]

x = 20

Therefore, the teacher bought 20 of the cheaper calculators.

Answer:

A very large amount of energy is produced from a series of chemical reactions.

Explanation:

Nuclear fission is the process of splitting apart nuclei (usually large nuclei). When large nuclei, such as uranium-235, fissions, energy is released. So much energy is released that there is a measurable decrease in mass, from the mass-energy equivalence. This means that some of the mass is converted to energy.

Answer:

2nd option

Explanation:

Nuclear fission is the process of splitting apart nuclei (usually large nuclei). When large nuclei, such as uranium-235, fissions, energy is released. So much energy is released that there is a measurable decrease in mass, from the mass-energy equivalence. This means that some of the mass is converted to energy.

Hello There!

A chemical reaction is when one or more molecules combine and rearrange to create one or more molecules or substances.

A chemical reaction is when a reaction occurs that changes the make-up (basically what makes something that thing. For example you have chemical make-up that makes you you. If that make up changed then you wouldn't be you anymore) making what ever was reacted into a NEW product

For example digestion is a chemical reaction. Let's say that you eat a carrot. When digestion (the chemical reaction) is complete the carrot is no longer how it was when your first put it in your mouth. It has been broken down and the acid in your belly changed the chemical make up so that your body can use the carrot for energy

Now let's say that you shred a piece of paper. This is NOT a chemical reaction, because the shredded paper is still the paper it was before it was shredded

Hope this helped!

~Just a girl in love with Shawn Mendes

Answer:

bye

Explanation:

Answer:

89.0 g.

Explanation:

2Na + Cl₂ → 2NaCl,

It is clear that 2 mol of Na react with 1 mol of Cl₂ to produce 2 mol of NaCl.

no. of moles of Na = mass/molar mass = (35.0 g)/(22.989 g/mol) = 1.522 mol.

no. of moles of Cl₂ = mass/molar mass = (100.0 g)/(70.906 g/mol) = 1.41 mol.

From the balanced equation: Na reacts with Cl₂ with (2: 1) molar ratio.

∴ 1.522 mol of Na "limiting reactant" reacts completely with 0.761 mol of Cl₂ "excess reactant".

2 mol of Na produces → 2 mol of NaCl, from stichiometry.

∴ 1.522 mol of Na produces → 1.522 mol of NaCl.

∴ The mass of the produced salt (NaCl) = (no. of moles)(molar mass) = (1.522 mol)(58.44 g/mol) = 88.95 g ≅ 89.0 g.

Final answer:

To find the maximum amount of NaCl produced from 35.0g of Na and 100.0g of Cl2, determine the limiting reactant and calculate the moles to find the answer of 75.8g.

Explanation:

To determine the maximum amount of NaCl that can be produced from 35.0g of Na and 100.0g of Cl2, you need to identify the limiting reactant in the reaction.

The molar mass of NaCl is 58.44g/mol, so we can calculate the moles of Na and Cl2 to see which one will run out first, limiting the amount of NaCl produced.

The maximum amount of NaCl that can be produced is 75.8g.

Answer:

95.3 grams.

Explanation:

Relative atomic mass data from a modern periodic table:

How many moles of Na are consumed?

[tex]M(\mathrm{Na}) = \rm 22.990\; g\cdot mol^{-1}[/tex].

[tex]\displaystyle n(\mathrm{Na}) = \frac{m(\mathrm{Na})}{M(\mathrm{Na})} = \rm \frac{70.7\; g}{22.990\;g\cdot mol^{-1}}=3.07525\;mol[/tex].

How many moles of [tex]\mathrm{Na_2 O}[/tex] formula units will be produced?

Consider the ratio between the coefficient of [tex]\mathrm{Na_2 O}[/tex] and that of [tex]\mathrm{Na}[/tex] in the equation:

[tex]\displaystyle \frac{n(\mathrm{Na_2 O})}{n(\mathrm{Na})} = \frac{2}{4} = \frac{1}{2}[/tex].

As a result,

[tex]\displaystyle n(\mathrm{Na_2 O}) = n(\mathrm{Na}) \cdot \frac{n(\mathrm{Na_2 O})}{n(\mathrm{Na})} = \rm \frac{1}{2}\times 3.07525\;mol = 1.53763\; mol[/tex].

What will be the mass of that many [tex]\mathrm{Na_2 O}[/tex]?

Formula mass of [tex]\mathrm{Na_2 O}[/tex]:

[tex]M(\mathrm{Na_2 O}) = \rm 2\times 22.990 + 15.999 = 61.979\; g\cdot mol^{-1}[/tex].

[tex]m(\mathrm{Na_2 O}) = n(\mathrm{Na_2 O})\cdot M(\mathrm{Na_2 O}) = \rm 1.53763\; mol\times 61.979\; g\cdot mol^{-1} \approx 95.3\; g[/tex].

Answer: 95,3 g. would be produced, if the mass of Na = 70,7 g.

Answer:

1125mL

Explanation:

this can be done using general gas law

Answer:

The absolute temperature  of the gas will be affected by a fourfold increase.

The pressure must be applied at 450 K should be 1,125 torr.

Explanation:

Charles's Law consists in the relationship between the volume and temperature of a certain amount of ideal gas, which is maintained at a constant pressure, by means of a constant of proportionality that is applied directly. For a given sum of gas at a constant pressure, as the temperature increases, the volume of the gas increases and when the temperature decreases, the volume of the gas decreases because the temperature is directly related to the energy of the movement of the gas molecules .

In summary, Charles's law is a law that says that when the amount of gas and pressure remain constant, the ratio between volume and temperature will always have the same value:

[tex]\frac{V}{T} =k (constant)[/tex]

If you double the volume of a gas sample and  then doubled the volume again, then the volume was increased four times. To comply with Charles's Law and maintain the relationship between volume and constant temperature, the temperature must increase four times, in the same way as volume.

So the absolute temperature  of the gas will be affected by a fourfold increase.

Gay-Lussac's law can be expressed mathematically as follows:

[tex]\frac{P}{T} =k[/tex]

Where P = pressure, T = temperature, K = Constant

This law indicates that the ratio between pressure and temperature is constant.

This law indicates that, as long as the volume of the container containing the gas is constant, as the temperature increases, the gas molecules move faster. Then the number of shocks against the walls increases, that is, the pressure increases. That is, the gas pressure is directly proportional to its temperature.

In short, when there is a constant volume, as the temperature increases, the gas pressure increases. And when the temperature decreases, gas pressure decreases.

When studying two different states of a gas, you have a gas that is at a pressure P1 and at a temperature T1 at the beginning of the experiment. When the temperature varies to a new T2 value, then the pressure will change to P2. This is true:

[tex]\frac{P1}{T1} =\frac{P2}{T2}[/tex]

So in this case, as the volume is constant, Gay-Lussac's law can be applied as follows:

[tex]\frac{750 torr}{300 K} =\frac{P2}{450 K}[/tex]

Then

[tex]P2=\frac{750 torr}{300 K} *450 K\\[/tex]

P2=1,125 torr

The pressure must be applied at 450 K should be 1,125 torr.

C. alpha = nucleus of a helium atom

beta = electron

gamma = photon

Answer : The correct option is, (C) alpha = nucleus of a helium atom, beta = electron,  gamma = photon

Explanation :

Alpha particle : It is also known as alpha radiation or alpha ray that consists of 2 protons and 2 neutrons that are bound together into a particle that is identical to the helium nucleus. It is produced in the process of alpha decay.

Beta particle : It is also known as beta radiation or beta ray. During the beta decay process, a high energy and speed electron or positron are emitted by the radioactive decay of atomic nucleus.

Gamma particle : It is also a gamma radiation or gamma ray that is arising from the radioactive decay of atomic nuclei. It has shortest wavelength waves and imparts high photon energy can pass through most forms of matters because they have no mass.

Hence, the correct option is, (C) alpha = nucleus of a helium atom, beta = electron,  gamma = photon

To find the current through the nightlight bulb, you can use Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). The current through the bulb is approximately 0.02917 Amperes, or 29.17 milliamperes (mA).

To find the current through the nightlight bulb, you can use Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the resistance is equal to the power (P) divided by the voltage (V). So, the current (I) can be calculated as follows:

I = P / V

Substituting the values given, we have:

I = 3.5 watts / 120.0 volts

Calculating this equation, we find that the current through the bulb is approximately 0.02917 Amperes, or 29.17 milliamperes (mA).

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Answer:

The solution can be prepared by adding 150.0 mL of isopropyl alcohol to 350.0 mL of water to make 30.0% isopropyl alcohol aqueous solution.

Explanation:

∵ The volume% of a solution = [(volume of the solute(isopropy)/(volume of the solution)] x 100.

The volume % = 30.0%, volume of the solution = 500.0 mL.

∴ Volume of the solute = (the volume% of a solution)(volume of the solution)/100 = (30.0%)(500.0 mL)/100 = 150.0 mL.

∵ The volume of solution = volume of the solute + volume of water

∴ Volume of water = volume of the solution - volume of the solute = (500.0 mL) - (350.0 mL) = 150.0 mL.

Final answer:

To prepare a 500.0mL solution of 30.0% isopropyl alcohol by volume, measure 150.0 mL of pure isopropyl alcohol, add it to a 500 mL volumetric flask, fill the flask to the mark with distilled water, and mix well.

Explanation:

To prepare 500.0mL of a 30.0% isopropyl alcohol by volume aqueous solution, you'll need to calculate the volume of pure isopropyl alcohol required and then make up the rest of the volume with water. Here is a step-by-step procedure:

By following these steps, you will have successfully prepared a 500.0mL solution of 30.0% isopropyl alcohol by volume.

Answer:

37.67 g.

Explanation:

CaH₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + 2H₂(g).

It is clear that 1 mol of CaH₂(s) reacts with 2 mol of H₂O(l) to produce 1 mol of Ca(OH)₂(aq) and 2 mol of H₂(g).

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm (P = 0.995 atm).

V is the volume of the gas in L (V = 45.0 L).

n is the no. of moles of the gas in mol (n = ??? mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K).

T is the temperature of the gas in K (T = 32.0° + 273 = 305.0 K).

∴ n = PV/RT = (0.0995 atm)(45.0 L)/(0.0821 L.atm/mol.K)(305.0 K) = 1.79 mol.

1 mol of CaH₂(s) produces → 2 mol of H₂(g), from stichiometry.

??? mol of CaH₂(s) produces → 1.79 mol of H₂(g).

∴ no. of moles of CaH₂(s) needed = (1 mol)(1.79 mol)/(2 mol) = 0.895 mol.

∴ mass of CaH₂ = (no. of moles)(molar mass of CaH₂) = (0.895 mol)(42.094 g/mol) = 37.67 g.

Approximately 37.5 grams of Calcium Hydride (CaH2) are needed to produce 45.0 L of Hydrogen gas at a pressure of 0.995 atm and a temperature of 32 °C.

The subject of this question is the calculation of the mass of Calcium Hydride (CaH2) required to generate a specific volume of Hydrogen gas (H2) under certain conditions. According to the ideal gas law, PV = nRT, we can find the number of moles of hydrogen (n) needed. Given P=0.995 atm, V=45.0 L, R=0.0821 (the ideal gas constant in terms of atm, L, mol, K), and T = 32°C = 305.15 K, n = (P*V)/(R*T) which gives approximately 1.78 moles of hydrogen.

From the balanced chemical equation, we know that 1 mole of CaH2 produces 2 moles of H2. Therefore, we need 0.89 moles of CaH2 to produce 1.78 moles of H2. Knowing that the molar mass of CaH2 is approximately 42.1 g/mole, the mass needed can be calculated as: mass = moles * molar mass = 0.89 moles * 42.1 g/mole = approx. 37.5 g. Hence, approx. 37.5 grams of CaH2 are needed to generate 45.0 L of H2 at a pressure of 0.995 atm and a temperature of 32 °C.

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Answer:

Plasma

Explanation:

Mostly this occurs at very high temperatures that cause atoms to lose electrons. Plasma is therefore a gas but of ions. Plasma can conduct electricity and can be influenced by magnetic fields. Plasma occurs mostly in stars where it is the dominant state of matter.  

Answer:

Plasma

Explanation:

Answer via Founder's Education/ Educere. Plasma fits the definition of the answer because it contains both positive and negitive free-flowing charges.

Answer:

762.55 g.

Explanation:

3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O.

It is clear that 3 mol of Cu reacts with 8 mol of HNO₃ to produce 3 mol of Cu(NO₃)₂, 2 mol of NO, and 4 mol of H₂O.

Using cross multiplication:

3 mol of Cu produce → 4 mol of H₂O, from stichiometry.

??? mol of Cu produce → 16 mol of H₂O.

∴ no. of moles of Cu needed = (3 mol)(16 mol)/(4 mol) = 12 mol.

∴ mass of Cu = (no. of moles)(atomic mass of Cu) = (12 mol)(63.546 g/mol) = 762.55 g.

Answer:The appearance of lines in an emission spectrum is caused by the fact that light is released as an electron moves to a lower energy state. When the atoms absorb energy they get excited and reach a higher level of energy. Then, when those atoms that are unstable release energy they pass to a lower level and emit light.

The appearance of lines in an emission spectrum​ is caused by the gas cloud on its own, without a light source behind it.

Hence, the appearance of lines in an emission spectrum​ is caused by the gas cloud on its own, without a light source behind it.

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The unknown volatile liquid in your Dumas flask is most likely water due to its molar mass of approximately 18 g/mol

The identity of the unknown volatile liquid in your Dumas flask can be determined using the ideal gas law equation PV=nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in kelvins. By rearranging this equation to n=m/M, we can find the molar mass (M). With your provided figures (change in mass = 27.4593 g - 27.0928 g, V=0.104L, P=0.976 atm, T=18°C + 273=291K), we find M=~18 g/mol. This molar mass is most closely correlated to the organic compound known as Water (H2O).

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Answer:

b. s,p,d

Explanation:

The type of orbitals found in the principal energy level n=3 is s, p and d orbitals.

Principal quantum number(n) denotes the energy level in which an orbital is located.

The principal quantum numbers takes values from n = 1, 2,3,4............

For example, the orbitals found in the principal quantum number with a value of 1 is s.

For n = 2, we have s and p

For n = 3, it is given as s, p and d

For n = 4, we have s, p, d and f

Answer:

It's B.

Explanation:

Hope my answer has helped you!

Answer:

B the attraction of metal ions to mobile electrons

Explanation:

Metal bonding occurs when metals are combined with each other. Metal atoms need to give up electrons to reach the configuration of a noble gas. In this case, the metals lose the valence electrons and an electron cloud (also called electron sea) is formed between the positive nuclei

Metals tend to lose the electrons of the last level forming positive ions. When ions are grouped neatly forming a network that is surrounded by the cloud of ceded electrons and a metallic bond is formed

Therefore the correct answer is the B the attraction of metal ions to mobile electrons