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3 years ago

Why is toast a chemical change?

1 answer:

4 0

Toast is a chemical change because of the chemical changes happening in the bread as it is toasted. This means its molecules are changing and breaking apart.

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Deep sea divers use a mixture of helium and oxygen to breathe. Assume that a diver is going to a depth of 150 feet where the tot

Svetlanka [38]

Answer:

4.525% is the percentage by volume of oxygen in the gas mixture.

Explanation:

Total pressure of the mixture = p = 4.42 atm

Partial pressure of the oxygen = $p_1=0.20 atm$

Partial pressure of the helium = $p_2$

$p_1=p\times \chi_1$ (Dalton law of partial pressure)

$0.20 atm=4.42 atm\times \chi_1$

$\chi_1=\frac{0.20 atm}{4.42 atm}=0.04525$

$\chi_2=1-\chi_1=1-0.04525=0.95475$

$chi_1+chi_2=1$

$n_1=0.04525 mol,n_2=0.95475 mol$

According Avogadro law:

$Moles\propto Volume$ (At temperature and pressure)

Volume occupied by oxygen gas = $V_1$

Total moles of gases = n = 1 mol

Total Volume of the gases = V

$\frac{n_1}{V_1}=\frac{n}{V}$

$\frac{V_1}{V}=\frac{n_1}{n}=\frac{0.04525 mol}{1 mol}$

Percent by volume of oxygen in the gas mixture:

$\frac{V_1}{V}\times 100=\frac{0.04525 mol}{1 mol}\times 100=4.525\%$

6 0

4 years ago

When sound waves move through a medium, in what direction to do the particles in the medium move?

-BARSIC- [3]

Longitudinal waves $$$$$

7 0

3 years ago

Read 2 more answers

help asap show work | a gas with a volume of 13L at a pressure of 197 kPA is allowed to expand to a volume of 23L. what is the p

Lera25 [3.4K]

Answer:

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

$P_1V_1 = P_2V_2$

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we're finding the new pressure

$P_2 = \frac{P_1V_1}{V_2} \\$

We have

$P_2 = \frac{13 \times 197000}{23} = \frac{2561000}{23} \\ = 111347.826...$

We have the final answer as

Hope this helps you

5 0

3 years ago

the mechanism for a chemical reaction is shown above. which of the following statements about the overall reaction and rate laws

Naddika [18.5K]

The rate equation of reaction is 2H2O2 → 2 H2O + O2 and the rate law for elementary step 1 is rate=k[H2O2][I−] .

The question is incomplete, the complete question is;

Step 1: H2O2 + I− → IO− + H2O

Step 2: H2O2 + IO− →H2O + O2 + I−

The mechanism for a chemical reaction is shown above. Which of the following statements about the overall reaction and rate laws of the elementary reactions is correct?

A) The chemical equation for the overall reaction is 2 H2O2+I−→ 2 H2O+O2+I− , and the rate law for elementary step 2 is rate=k[H2O2][IO−] .

B) The chemical equation for the overall reaction is H2O2+IO−→ H2O+O2+I− , and the rate law for elementary step 2 is rate=k[H2O2]2[IO−] .

C) The chemical equation for the overall reaction is 2 H2O2→2 H2O+O2 , and the rate law for elementary step 1 is rate=k[H2O2][I−] .

D) The chemical equation for the overall reaction is 2 H2O2→2 H2O+O2 , and the rate law for elementary step 1 is rate=k[H2O2]2 .

It is possible that a chemical reaction may not take place in a single reactive encounter. In that case, we can deduce the sequence of steps by which the reaction occurs. Each step is called an elementary reaction.

The overall rate law is the sum of all the elementary reactions after the intermediates have been eliminated. In this case, the specie IO− is an intermediate. Also, I− appears on both sides of the reaction equation and it has to cancel out.

The rate equation of reaction is 2H2O2 → 2H2O + O2 and the rate law for elementary step 1 is rate=k[H2O2][I−] .

Learn more: brainly.com/question/13309369

8 0

3 years ago

A sample of O2, under occupies 500ml at 25.0°C. What volume will the sample occupy at 0.0°C

NeX [460]

Answer:

458ml

Explanation:

According to charles law, $\frac{V_{1}}{T_{1}} =\frac{V_{2}}{T_{2}}$