Everything Science Grade 10

CHAPTER 19. QUANTITATIVE ASPECTS OF CHEMICAL CHANGE 19.4

n=C×V= 0, 01 mol·dm−^3 × 0 , 5 dm−^3 = 0, 005 mol

Step 3:Find the mass

m=n×M= 0, 005 mol× 58 , 45 g·mol−^1 = 0, 29 g

The mass of sodium chloride needed is 0 , 29 g

Exercise 19 - 6

1. 5 , 95 g of potassium bromide was dissolved in 400 cm^3 of water. Calculate

its concentration.

2. 100 g of sodium chloride (NaCl) is dissolved in 450 cm^3 of water.

a. How many moles of NaCl are present in solution?

b. What is the volume of water (in dm^3 )?

c. Calculate the concentration of the solution.

3. What is the molarity of the solution formed by dissolving 80 g of sodium

hydroxide (NaOH) in 500 cm^3 of water?

4. What mass (g) of hydrogen chloride (HCl) is needed to make up 1000 cm^3

of a solution of concentration 1 mol·dm−^3?

5. How many moles of H 2 SO 4 are there in 250 cm^3 of a 0 , 8 mol·dm−^3

sulphuric acid solution? What mass of acid is in this solution?

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Stoichiometric

calculations

ESAGF

Stoichiometry is the calculation of the quantities of reactants and products in chemical

reactions. It is important to know how much product will be formed in a chemical reaction,

Chemistry: Chemical change 353