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2 years ago

Which of the following is an example of a physical change?

Chemistry

1 answer:

Pavel [41]2 years ago

3 0

Answer:

A. A solid dissolves.

Explanation:

The physical change from the given choices is that a solid dissolves.

The dissolution of a solute in a solvent is a physical change and not a chemical change.

A physical change has the following properties:

they are easily reversible
leads to the production of no new kinds of matter
involves no change in mass
requires little energy

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What total volume of ozone measured at a pressure of 24.5 mmHg and a temperature of 232 K can be destroyed when all of the chlor

ddd [48]

Answer:

$1.75272\ \text{m}^3$

Explanation:

The breakdown reaction of ozone is as follows

$CF_3Cl + UV \rightarrow CF_3 + Cl$

$Cl + O_3 \rightarrow ClO + O_2$

$O_3 + UV \rightarrow O_2 + O$

$ClO + O \rightarrow Cl + O_2$

It can be seen that 2 moles of ozone is required in the complete cycle

So for 10 cycles, 20 moles of ozone is required

m = Mass of $CF_3Cl$ = 15.5 g

M = Molar mass of $CF_3Cl$ = 104.46 g/mol

P = Pressure = 24.5 mmHg

T = Temperature = 232 K

R = Gas constant = $62.363\ \text{L mmHg/K mol}$

Number of moles is given by

$n=\dfrac{m}{M}\\\Rightarrow n=\dfrac{15.5}{104.46}\\\Rightarrow n=0.1484\ \text{moles}$

$20\ \text{moles} = 20\times 0.1484 = 2.968\ \text{moles}$

From ideal gas law we have

$PV=nRT\\\Rightarrow V=\dfrac{nRT}{P}\\\Rightarrow V=\dfrac{2.968\times 62.363\times 232}{24.5}\\\Rightarrow V=1752.72\ \text{L}=1.75272\ \text{m}^3$

For 20 cycles of the reaction the volume of the ozone is $1.75272\ \text{m}^3$ .

7 0

2 years ago

Map<br> Formulate your hypothesis.<br> List down the materials.<br> • Write the methods.

Whitepunk [10]

Answer:

How to Formulate an Effective Research Hypothesis

State the problem that you are trying to solve. Make sure that the hypothesis clearly defines the topic and the focus of the experiment.

Try to write the hypothesis as an if-then statement. ...

Define the variables.

Explanation:

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2 years ago

Choose the aqueous solution below with the highest freezing point. These are all solutions of nonvolatile solutes and you should

GrogVix [38]

Answer:

0.200 m K3PO3

Explanation:

Let us remember that the freezing point depression is obtained from the formula;

ΔTf = Kf m i

Where;

Kf = freezing point constant

m = molality

i = Van't Hoff factor

The Van't Hoff factor has to do with the number of particles in solution. Let us consider the Van't Hoff factor for each specie.

0.200 m HOCH2CH2OH - 1

0.200 m Ba(NO3)2 - 3

0.200 m K3PO3 - 4

0.200 m Ca(CIO4)2 - 3

Hence, 0.200 m K3PO3 has the greatest van't Hoff factor and consequently the greatest freezing point depression.

8 0

2 years ago

PLEASE HELP, THIS IS TIMED!!!!!!!!!!!!!!!!!!!!!!!!!!Convert 22.6g AgNO3 to moles.

andreev551 [17]

Answer:

the answer b because

The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles AgNO3, or 169.8731 grams.

Explanation:

5 0

3 years ago

Excess reagent definition

victus00 [196]

The reactant in a chemical reaction that limits the amount of product that can be formed. The reaction will stop when all of the limiting reactant is consumed

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3 years ago