Molar Mass & Molar Volume
Name:
Q1.
Date:
Q2.
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Molar Mass & Molar Volume
Q3. Period 3 contains the elements sodium to argon. This question asks about the chemistry
of each of the Period 3 elements or their compounds.
(a) Sodium nitrate is a white crystalline solid. When heated it melts and the following
reaction occurs.
2NaNO3(l) → 2NaNO2(l) + O2(g)
A 3.40 g sample of sodium nitrate is heated.
Calculate the
• number of moles of NaNO3 used,
.................................. mol
• number of moles of O2 formed,
• volume of O2 formed, in dm3 (measured at r.t.p.).
.................................. mol
.................................. dm3
Q4. Barium carbonate decomposes when heated.
BaCO3(s)→ BaO(s) + CO2(g)
(a) A student heated a 10.0 g sample of barium carbonate until it was fully decomposed.
(i) Calculate the number of moles of barium carbonate the student used.
moles of barium carbonate = ............................. mol
(ii) Calculate the volume of carbon dioxide gas produced at room temperature and pressure.
Give your answer in dm3.
volume of carbon dioxide = ............................. dm3
(b) The student added 2.00 g of the barium oxide produced to water.
BaO + H2O → Ba(OH)2
Calculate the mass of barium hydroxide that can be made from 2.00 g of barium oxide. The
Mr of Ba(OH)2 is 171.
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Molar Mass & Molar Volume
mass of barium hydroxide = ............................. g
(c) A 1.50 g sample of barium hydroxide was dissolved in water. The total volume of the
solution was 100 cm3.
A 25.0 cm3 portion of the barium hydroxide solution was titrated against hydrochloric acid.
The volume of hydrochloric acid required was 18.75 cm3.
Ba(OH)2 + 2HCl →BaCl 2 + 2H2O
(i) Calculate how many moles of barium hydroxide were in the 25.0 cm3 portion used in the
titration.
moles of barium hydroxide = ............................. mol
(ii) Calculate the concentration of the hydrochloric acid used.
concentration of hydrochloric acid = ............................. mol / dm3
Q5. A teacher heated 18.8 g of copper(II) nitrate.
(i) Complete the chemical equation for the reaction.
2Cu(NO3)2 →
O2 + ......NO2 + ......................
(i) Calculate the number of moles of copper(II) nitrate present in the 18.8 g.
.............................. mol
(ii) Calculate the maximum number of moles of oxygen that can be made by heating 18.8 g of
copper(II) nitrate.
.............................. mol
(iii) Calculate the maximum volume of oxygen at room temperature and pressure, in cm3, that
can be made by heating 18.8 g of copper(II) nitrate.
.............................. cm3
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Molar Mass & Molar Volume
Q6
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