Define the term relative atomic mass, Ar, of an element.
Metal carbonates have a variety of medicinal applications.
Magnesium and calcium carbonate are often used to treat heartburn and indigestion. Iron carbonate is used as a dietary supplement to treat anaemia. Lithium carbonate can be used in the treatment of mental health illnesses.
Write a balanced symbol equation, including state symbols, for the reaction of calcium carbonate with hydrochloric acid to form calcium chloride and two other products.
A student wants to find the mass of magnesium carbonate in a 500 mg indigestion tablet. She crushes the tablet and reacts it with 25 cm3 of 1.00 mol dm-3 sulfuric acid according to the following equation:
MgCO3 + H2SO4 → MgSO4 + H2O + CO2
i) Calculate the number of moles of magnesium carbonate in the tablet.
You can assume that the magnesium carbonate is responsible for all of the tablet's mass.
ii) Calculate the number of moles of sulfuric acid that the tablet reacts with.
iii) Explain how your answers to parts (i) and (ii) show that the sulfuric acid is in excess.
The student then titrated the excess sulphuric acid with 0.5 mol dm3 sodium hydroxide solution. The student’s titration results are shown in Table 1.
Table 1
Titration number | Initial volume / cm3 | Final volume / cm3 | Titre / cm3 |
Rough | 0.00 | 21.70 | 21.70 |
1 | 21.70 | 43.05 |
|
2 | 0.10 | 21.60 |
|
3 | 21.60 | 43.00 |
|
4 | 0.05 | 21.40 |
|
i) Complete the table by calculating the titres.
ii) Calculate the average titre using concordant results.
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