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3 years ago

H2O has a mc021-1.jpgHvap = 40.7 kJ/mol. What is the quantity of heat that is released when 27.9 g of H2O condenses?

Chemistry

2 answers:

Gelneren [198K]3 years ago

7 0

Answer:

C- 63.09 kJ

Explanation:

I have several degrees

babymother [125]3 years ago

5 0

Energy released from changing the phase of a substance from the gas phase to liquid phase can be calculated by using the specific latent heat of vaporization. The heat of fusion of water at 0 degrees Celsius is 40.7 kJ/mol. Calculation are as follows:

Energy = 27.9 g (1 mol / 18.02 g) x 40.7 kJ/mol

Energy = 63.09 kJ

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Answer:

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Explanation:

Yo know the following balanced reaction:

CuSO₄(aq)+ Zn(s) →Cu(s) + ZnSO₄(aq)

You can see that by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of reagents and products are part of the reaction:

CuSO₄: 1 mole
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the molar mass of the compounds participating in the reaction is:

CuSO₄:63.54 g/mole + 32 g/mole + 4*16 g/mole= 159.54 g/mole ≅ 160 g/mole
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Cu: 63.54 g/mole
ZnSO₄: 65.37 g/mole + 32 g/mole + 4*16 g/mole= 161.37 g/mole

Then, by stoichiometry of the reaction, the following amounts of mass of reagent and product participate in the reaction:

CuSO₄: 1 moles* 160 g/mole= 160 g
Zn: 1 mole* 65.37 g/mole= 65.37 g
Cu: 1 mole* 63.54 g/mole= 63.54 g
ZnSO₄: 1 mole* 161.37 g/mole= 161.37 g

Now you can apply the following rule of three: if 160 grams of CuSO₄ react with 65.37 grams of Zn by this reaction stoichiometry, 454 grams of CuSO₄ with how much mass of Zn will it react?

$mass of Zn=\frac{454 grams of CuSO_{4} *65.37 grams of Zn}{160 grams of CuSO_{4}}$

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Answer:

Of the following substances, PCl₃ has the highest boiling point

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The given substances and their boiling point from online resources are;

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Based on the freezing point depression equation:

ΔT = Kf*m*i

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And i is Van't Hoff factor (1 for nonelectrolyte solutes)

Replacing:

1.87°C = 1.86°CKg/mol*m*i

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Molar mass is defined as the ratio between mass of a substance in grams and moles, that is:

45.2g / 0.479mol =

<h3>94.4g/mol is molar mass of the unknown</h3>

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