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2 years ago

1. Which of the following is an example of a physical change to matter?

Chemistry

2 answers:

sertanlavr [38]2 years ago

6 0

1. C. Freezing
2. B. Dissolving salt in water

Ostrovityanka [42]2 years ago

4 0

Answer:

1) FREEZING

2)DISOLVING SALT IN WATER

Explanation:

A physical change is the one that can be easily reversed and there is no new substance formed. However , physical change can always be reversible.

For instance the separation of mixtures by evaporation is physical change.

As we have physical change there is also a chemical change which a change that's cannot be reversed easily and there's no new substance formed. Examples are addition of water to quicklime, fermentation of substance,melting a stick of butter

,using magnesium to displace hydrogen gas from water.

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Answer is: activation energy of this reaction is 212,01975 kJ/mol.
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T₁ = 622 K.

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1/T₁ = 1/622 K = 0,0016 1/K.
1/T₂ = 1/666 K = 0,0015 1/K.
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A 50.0 mL sample of a 1.00 M solution of CuSO4 is mixed with 50.0 mL of 2.00 M KOH in a calorimeter. The temperature of both sol

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Answer : The enthalpy change for the process is 52.5 kJ/mole.

Explanation :

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$q=[q_1+q_2]$

$q=[c_1\times \Delta T+m_2\times c_2\times \Delta T]$

where,

q = heat released by the reaction

$q_1$ = heat absorbed by the calorimeter

$q_2$ = heat absorbed by the solution

$c_1$ = specific heat of calorimeter = $12.1J/^oC$

$c_2$ = specific heat of water = $4.18J/g^oC$

$m_2$ = mass of water or solution = $Density\times Volume=1/mL\times 100.0mL=100.0g$

$\Delta T$ = change in temperature = $T_2-T_1=(26.3-20.2)^oC=6.1^oC$

Now put all the given values in the above formula, we get:

$q=[(12.1J/^oC\times 6.1^oC)+(100.0g\times 4.18J/g^oC\times 6.1^oC)]$

$q=2623.61J$

Now we have to calculate the enthalpy change for the process.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat released = 2626.61 J

n = number of moles of copper sulfate used = $Concentration\times Volume=1M\times 0.050L=0.050mole$

$\Delta H=\frac{2623.61J}{0.050mole}=52472.2J/mole=52.5kJ/mole$

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