Reacting Masses & Volumes (of Solutions & Gases) (CIE A Level Chemistry)

A volume of nitrogen gas, 2.00 dm³ measured under standard conditions, was reacted with a large volume of hydrogen gas, to produce ammonia. Only 15.0% of the nitrogen gas reacted to produce ammonia.

What mass of ammonia was made?

Excess aqueous cold sodium hydroxide is reacted with 0.125 mol of chlorine gas, Cl₂. One of the products is a compound of sodium, oxygen and chlorine.

What mass of the product is formed?

When heated magnesium nitrate, Mg(NO₃)₂, will decompose to a white solid and a mixture of gases. One of the gases released is an oxide of nitrogen, X.

7.4 g of anhydrous magnesium nitrate is heated until no further reaction takes place.

What is the mass of X produced?

Excess water and 0.144 g of an aluminium compound X were reacted to form a gas. The gas burns completely in O₂ to form H₂O and 72 cm³ of CO₂ only. The volume of CO₂ was measured at room temperature and pressure.

What is the formula for X?

A metal element of mass 1.15 g reacted with 300 cm³ of oxygen at room conditions, to form an oxide which contains O^2- ions.

Which one of these is the metal?

Solid fertilisers often contain the elements N, P and K in a ratio of 15 g: 30 g: 15 g per 100 g of fertiliser. It is recommended that the fertiliser is used at 14 g of fertiliser per 5 dm³ of water.

What is the concentration of nitrogen atoms in the solution?

1.00 g of carbon is combusted in a limited supply of oxygen. 0.50 g of the carbon combusts to form CO₂ and 0.50 g of the carbon combusts to form CO.

These were passed through excess NaOH (aq) and the remaining gas then dried and collected.

Assuming that all gas volumes were taken at  room conditions, what was the volume of gas at the end of the reaction?

Chicken eggs are made up of 5% by mass. The average egg has a mass of 50 g. 

Assume that chicken eggshell is pure calcium carbonate.

How many complete chicken eggshells would be needed to neutralise 50 cm³ of 2.0 mol dm^-3 ethanoic acid?

When a sample potassium oxide, K₂O, is dissolved in 250 cm³ of distilled water. 25 cm³ of this solution is titrated against sulfuric acid with concentration of 2.00 mol dm^-3. Complete neutralisation takes place with 15 cm³ of sulfuric acid.

What is the mass of the original sample of potassium oxide dissolved in 250 cm³ of distilled water?

Excess acidified aqueous potassium dichromate(VI) was mixed with 2.76 g of ethanol. The reaction mixture was then boiled under reflux for one hour. The organic product was collected by distillation.

The yield of the product was 75.0%

What is the mass of the product collected?

The concentration of calcium ions in a sample of water can be determined by using an ion-exchange column, shown in the diagram below:

A 50 cm³ sample of water was passed through the ion-exchange resin, this contained dissolved calcium sulfate

Each calcium ion in the sample was exchanged for two hydrogen ions. The resulting acidic solution collected in the flask required 25 cm³ of 1.0 x 10^-2 mol dm^-3 potassium hydroxide for complete neutralisation.

What was the concentration of the calcium sulfate in the original sample?

Bromide ions are oxidised to bromine by lead (IV) chloride. The Pb⁴⁺ ions are reduced to Pb²⁺ ions in this reaction.

If 6.980 g of lead (IV) chloride is added to an excess of sodium bromide solution, what mass of bromine would be produced?

10 cm³ of methane and 10 cm³ of ethane were sparked with an excess of oxygen. Once cooled the remaining gas was passed through aqueous potassium hydroxide.

Assuming all measurements were taken at 25˚C and 1 atm pressure.

What volume of gas is absorbed by the alkali?

A solution of Sn²⁺ ions will reduce MnO₄^- ions to Mn²⁺ ions when acidified. The Sn²⁺  ions are oxidised to Sn⁴⁺ ions in this reaction.

How many moles of Mn²⁺ ions are formed when a solution containing 9.5 g of SnCl₂
(M_r: 190) is added to an excess of acidified KMnO₄ solution?

Some fireworks can use the reaction between aluminium powder and anhydrous barium nitrate as a propellant. Metal oxides and nitrogen are the only products.

10Al + 3Ba(NO₃)₂ → 5Al ₂O₃ + 3BaO + 3N₂

When 0.783 g of anhydrous barium nitrate reacts with an excess of aluminium what is the volume of nitrogen produced?