Analysis of a sample of a chemical with formula C₂₂H₃₀N₆O₄S, showed that it contained 0.0195 mol of carbon.

What mass of nitrogen was present in the sample?

A solution of lead(ll) chloride (Mr = 278.2) contains 1.08 g of PbCl2 in 100 cm3 of solution. In this solution, the lead(ll) chloride is fully dissociated into ions.

What is the concentration of chloride ions in this solution?

What is the number of atoms in 0.0100 mol of NH³?

(The Avogadro constant L = 6.022 × 10²³ mol⁻¹)

Which of the following contains the most chloride ions?

Which of these contains the most molecules?

Which of the following contains the most chloride ions?

In an experiment to identify a Group 2 metal (X), 0.102 g of X reacts with an excess of aqueous hydrochloric acid according to the following equation.

X + 2HCl --> XCl₂ + H₂

The volume of hydrogen gas given off is 65 cm³ at 99 kPa pressure and 303 K. The gas constant is R = 8.31 J K^–1 mol^–1. Which is X?

In a car airbag, sodium azide (NaN₃) decomposes to form sodium metal and nitrogen gas.

2NaN₃(s) → 2Na(s) + 3N₂(g)

The sodium metal then reacts with potassium nitrate to produce more nitrogen gas.

10Na(s) + 2KNO₃(s) → N₂(g) + 5Na₂O(s) + K₂O(s)

If 2.00 mol of sodium azide react in this way, how many molecules of N₂ will be formed? (The Avogadro constant L = 6.022 × 10²³ mol^–1)

The M_r of hydrated copper sulfate (CuSO₄.5H₂O) is 249.6.

Which of the following is the mass of hydrated copper sulfate required to make 50.0 cm³ of a 0.400 mol dm⁻³ solution?

The removal of silicon dioxide with limestone in a blast furnace can be represented by the following equation.

CaCO₃(s) + SiO₂(s) → CaSiO₃(l) + CO₂(g)

The minimum mass of calcium carbonate needed to remove 1.00 tonne (1000 kg) of silicon dioxide is

The removal of silicon dioxide with limestone in a blast furnace can be represented by the following equation.

CaCO₃(s) + SiO₂(s) → CaSiO₃(l) + CO₂(g)

The volume of carbon dioxide, measured at 298 K and 1.01 × 10⁵ Pa, formed in this reaction during the removal of 1.00 tonne (1000 kg) of silicon dioxide is

Silver oxide, Ag₂O, can be reduced by passing hydrogen gas over the heated oxide. The maximum mass of silver that could be obtained from 2.32 g of silver oxide is

In a reaction which gave a 27.0% yield, 5.00 g of methylbenzene were converted into the explosive 2,4,6-trinitromethylbenzene (TNT) (M_r = 227.0). The mass of TNT formed was

Use the information below to answer this question.

A saturated solution of magnesium hydroxide, Mg(OH)₂, contains 0.1166 g of Mg(OH)₂ in 10.00 dm³ of solution. In this solution the magnesium hydroxide is fully dissociated into ions.

Which one of the following is the concentration of Mg²⁺(aq) ions in the saturated solution?

Which one of the following contains the greatest number of moles of methanol? (The Avogadro number (L) is 6.02 × 10²³, the relative molecular mass (M_r) of methanol is 32.)

A 385 cm³ sample of carbon dioxide at 100 kPa and 25 °C was mixed with 2.89 × 10⁻² mol of argon. The gas constant, R = 8.31 J K⁻¹ mol⁻¹

What is the mole fraction of carbon dioxide in the mixture?

A student is provided with 5.00 cm³ of 1.00 mol dm⁻³ ammonia solution. The student was asked to prepare an ammonia solution with a concentration of 0.050 mol dm⁻³

What volume of water should the student add?

130 cm³ of oxygen and 40 cm³ of nitrogen, each at 298 K and 100 kPa, were placed into an evacuated flask of volume 0.50 dm³.

What is the pressure of the gas mixture in the flask at 298 K?

A sample of 2.18 g of oxygen gas has a volume of 1870 cm³ at a pressure of 101 kPa.

What is the temperature of the gas? The gas constant is R = 8.31 J K^–1 mol^–1.

30 cm³ of xenon are mixed with 20 cm³ of fluorine. The gases react according to the following equation. Assume that the temperature and pressure remain constant.

Xe(g) + F₂(g) → XeF₂(g)

What is the final volume of gas after the reaction is complete?

The removal of silicon dioxide with limestone in the Blast Furnace can be represented by the following equation.

CaCO₃(s) + SiO₂(s) → CaSiO₃(l) + CO₂(g)

The volume of carbon dioxide, measured at 298 K and 1.01 × 10⁵ Pa, formed in this reaction during the removal of 1.00 tonne (1000 kg) of silicon dioxide is

An equation for the incomplete combustion of butane in oxygen is

C₄H₁₀ + 4.5O₂ → 4CO + 5H₂O

The volume in dm³ of oxygen at 295 K and 100 kPa required to burn 0.1 mol of butane to form steam and carbon monoxide only is

Sodium hydrogencarbonate decomposes on heating as shown by the equation below.

2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

The volume of carbon dioxide, measured at 298 K and 101 kPa, obtained by heating 0.0500 mol of sodium hydrogencarbonate is

What is the volume occupied by 10.8 g of the freon CCl₂F₂ at 100 kPa and 273 K?

What is the empirical formula of an oxide of nitrogen that contains 26% nitrogen by mass?

An organic compound is found to contain 40.0% carbon, 6.7% hydrogen and 53.3% oxygen.

Which of the following compounds could this be?

When TiCI₄ is reduced with hydrogen under certain conditions, a new compound is produced which contains 68.9% chlorine by mass. Which one of the following could be the formula of the new compound?

A student devised an experiment to find the concentration of sulfuric acid in a sample of battery acid.

• A measuring cylinder was used to transfer 10 cm³ of battery acid to a volumetric flask.

• Distilled water was added to the volumetric flask until the volume reached 250 cm³

• A 25.0 cm³ sample of diluted acid was transferred from the volumetric flask to a conical flask using a pipette.

• A few drops of methyl orange indicator were added to the acid in the conical flask before titrating the acid with sodium hydroxide.

• The titration was repeated five times but concordant results were not obtained. (Note: Methyl orange is red in acid and yellow in alkali.)

Which suggestion would improve the chances of obtaining concordant titres?

What is the burette reading for this transparent liquid?