What is the number of molecules in 500 cm3 of oxygen at standard temperature and pressure?
3.00 x 1023
3.00 x 1026
1.25 x 1021
1.34 x 1022
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Syllabus Edition
First teaching 2023
First exams 2025
What is the number of molecules in 500 cm3 of oxygen at standard temperature and pressure?
3.00 x 1023
3.00 x 1026
1.25 x 1021
1.34 x 1022
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A 5.62 g sample of anhydrous sodium sulfate, Na2SO4, is dissolved in water and the solution made up to 250 cm3 in a volumetric flask.
What is the concentration in mol dm-3 of the hydrated sodium sulfate solution?
0.61
1.6 x 10-4
0.16
0.016
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Methane and steam can be used to prepare hydrogen and carbon dioxide as shown by the equation below.
CH4 (g) + H2O (g) → 3H2 (g) + CO (g)
200 g of methane was reacted with an excess of steam to produce 642 dm3 of hydrogen gas at RTP.
What is the percentage yield of hydrogen?
71.3%
46.7%
33.3%
140.2%
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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?
2.83 g
1.42 g
0.455 g
0.213 g
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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?
13.3 g
9.31 g
18.6 g
26.6 g
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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?
4.6 g
1.5 g
2.3 g
3.0 g
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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?
Al2C3
Al3C4
Al5C3
Al4C3
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A metal element of mass 1.15 g reacted with 300 cm3 of oxygen at room conditions, to form an oxide which contains O2- ions.
Which one of these is the metal?
Calcium
Sodium
Potassium
Magnesium
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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?
0.42 mol dm-3
0.05 mol dm-3
0.03 mol dm-3
0.75 mol dm-3
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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?
3 dm3
2 dm3
1.5 dm3
1 dm3
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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?
4
3
2
1
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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?
56.6 g
47.1 g
28.3 g
2.83 g
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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?
1.98 g
2.70 g
2.07 g
4.80 g
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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?
4.0 x 10-2 mol dm-3
2.0 x 10-2 mol dm-3
1.0 x 10-2 mol dm-3
2.5 x 10-3 mol dm-3
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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?
3.196 g
6.392 g
0.799 g
1598 g
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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?
45 cm3
30 cm3
20 cm3
10 cm3
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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
(Mr: 190) is added to an excess of acidified KMnO4 solution?
0.010
0.015
0.020
0.050
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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?
144.0 cm3
93.6 cm3
1.62 cm3
72.0 cm3
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