# Inorganic Chemistry

Sulfuric acid H2SO4(aq) is described as a strong acid whereas hydrofluoric acid HF(aq) is described as a weak acid.

(a) (i) Describe what is meant by the terms strong and weak acid. (Two or three short sentences)

(ii) Write fully balanced equations for the equilibrium dissociation of both sulfuric and hydrofluoric acids in aqueous solution.

(b) Calculate the hydrogen ion concentration when 0.25 g of sulfuric acid is dissolved in sufficient water to make 1 dm3 of final solution. What is the pH of this solution? (Your answers should be given to 2 significant figures.)

(c) At 25 °C, the equilibrium constant Ka, for hydrofluoric acid is

7.2 × 10−4 mol dm−3 and the equilibrium concentration of HF(aq) is

0.01 mol dm−3. Calculate the equilibrium concentrations of H+(aq) and F−(aq) and hence the pH of the acid solution. (Your answer for pH should be given to 2 significant figures.)

Question 4

This question carries 20% of the marks for this assignment. It will be marked accordingly to how well you demonstrate in your answer the following learning outcomes:

Kn1 knowledge and understanding of acid and base reactions and pH, and of writing chemical formulas and equations and molar calculations.

C1 make sense of data, numerical and mathematical with respect to molar amounts and mass of chemical substances given in the question.

Ky1 use mathematical skills appropriate to the study of science at this level, in particular: processing data given for calculations involving molar amounts, concentration and logarithms.

#### Solution Summary

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