5.1 Avogadro’s number and the mole: Calculation problems

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Year 9 Chemistry, Worksheet 20

5.1 Avogadro’s number and the mole: Calculation problems

1. Calculate the molar mass, Mr for the following compounds;

a. NaOH b. CuSO4

c. C6H12

d. C3H5COOH

2. Calculating the mass percentage of an element in a compound a. % O in NaOH

b. % of O in CuSO4

c. % of H in C6H12

d. % of H in C3H5COOH

3. Calculate the percentage by mass of Nitrogen in the following fertilizers and compounds;

a. (NH4)2SO4

b. (NH4)3PO4

c. CO(NH2)2

d. CaCN2

e. CH2(NH2)COOH

BONUS: Balance The following equations

1. H

2

+ F

2

H F

2. N

2

+ H

2

N H

3

3. Al + O

2

Al

2

O

3

4. Mg + H

2

SO

4

Mg SO

4

+ H

2

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5. C + Cl

2

C Cl

4

6. P H

5

+ O

2

P

2

O

5

+ H

2

O

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List the given quantities (using symbols and units) and those needed to answer the following questions:

a) Calculate the mass of 3,5 moles of sulfur (S).

b) Determine the substance amount of copper sulfide (CuSO4) in 13 grams of substance.

c) Calculate the mass of sodium chloride (NaCl) in 150 ml of a sodium chloride solution with a concentration of 2,5 mols per litre.

List the equations necessary to perform the calculations for the questions above.

Perform the calculations.