Chemistry - Solution Questions - AS Level

AS1999

1. In an experiment, 2.601g of anhydrous sodium carbonate, Na2CO3 were dissolved in water and the solution made up to 250cm3 in a volumetric flask.
a. Calculate the molarity of the sodium carbonate solution (3 marks)
25.0cm3 of this sodium carbonate solution required 26.35cm3 of HCl for complete neutralisation.
b. Calculate the concentration of the acid in this experiment. (4 marks)
Na2CO3 + 2HCl → 2NaCl + CO2 + H2O

2. Write an equation to show the reaction between magnesium metal and sulphuric acid (1)
What mass of Mg will react completely with 100cm3 of 1M H2SO4? (2)
Calculate the volume of hydrogen gas produced, in cm3, when 4.8g of Mg reacts with excess acid at stp. (2)

3. Hydrochloric acid reacts with sodium carbonate according to the following equation
Na2CO3 + 2HCl → 2NaCl + CO2 + H2O
An ionic equation is
CO32- + H+ → CO2 + H2O
Give 2 reasons why this equation is not balanced. (2)
5.202g of anhydrous sodium carbonate were dissolved in water and the solution made up to exactly 500cm3 Calculate the concentration of this solution in mol dm-3. (3)
25cm3 of this solution were titrated against dilute HCl, 24.5cm3 were needed. Calculate the molarity of the acid. (3)
What mass of NaCl will be made from the reaction between 100cm3 HCl with excess sodium carbonate. (2)
PLEASE HELP <3

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