化學計量：莫耳與化學計量學：練習題

Calculate the mass of magnesium oxide (\(MgO\)) formed when \(2.4\) g of magnesium ribbon is completely burnt in excess oxygen.
(Relative atomic masses: \(Mg = 24.3, O = 16.0\))

When \(4.8\) g of magnesium reacts with excess dilute hydrochloric acid, what is the maximum volume of hydrogen gas produced at room temperature and pressure (r.t.p.)?
(Relative atomic mass: \(Mg = 24.3\); Molar volume of gas at r.t.p. = \(24.0\) \(dm^3\,mol^{-1}\))

A mixture of \(20\) \(cm^3\) of methane (\(CH_4\)) and \(60\) \(cm^3\) of oxygen (\(O_2\)) is ignited. After the reaction, the mixture is cooled to room temperature and pressure. What is the final volume of the gas mixture?
(Note: Water is liquid at room temperature; all gas volumes are measured at the same temperature and pressure.)

A sample of a metal oxide with the formula \(M_2O_3\) contains \(31.58\%\) oxygen by mass. Calculate the relative atomic mass of the metal \(M\).
(Relative atomic mass: \(O = 16.0\))

An aqueous solution of sodium hydroxide (\(NaOH\)) has a concentration of \(2.0\) \(mol\,dm^{-3}\). What volume of this solution is required to completely neutralize \(25.0\) \(cm^3\) of \(0.50\) \(mol\,dm^{-3}\) sulfuric acid (\(H_2SO_4\))?

Calculate the number of moles of atoms present in \(1.20 \times 10^{24}\) atoms of copper. (Avogadro constant \(L = 6.02 \times 10^{23} \text{ mol}^{-1}\))

What is the concentration in \(\text{mol dm}^{-3}\) of a solution prepared by dissolving \(5.85\) g of sodium chloride (\(NaCl\)) in water to make a \(250 \text{ cm}^3\) solution? (Relative atomic masses: \(Na = 23.0\), \(Cl = 35.5\))

An unknown organic compound consists of \(40.0\%\) carbon, \(6.7\%\) hydrogen, and \(53.3\%\) oxygen by mass. If the relative molecular mass is \(180\), determine the molecular formula. (Relative atomic masses: \(C = 12.0, H = 1.0, O = 16.0\))

Calculate the number of molecules and the total number of atoms present in \(8.8\) g of carbon dioxide (\(CO_2\)).
(Relative atomic masses: \(C = 12.0, O = 16.0\); Avogadro constant \(L = 6.02 \times 10^{23} \text{ mol}^{-1}\))

In an experiment, \(2.10 \text{ g}\) of magnesium carbonate (\(MgCO_3\)) was heated to decompose into magnesium oxide and carbon dioxide. Only \(0.80 \text{ g}\) of magnesium oxide (\(MgO\)) was actually obtained.
a) Write the balanced chemical equation for the decomposition.
b) Calculate the theoretical yield of \(MgO\).
c) Calculate the percentage yield of the reaction.
(Relative atomic masses: \(C = 12.0, O = 16.0, Mg = 24.3\))