group 1
Nitrous acid decomposes on heating.
•Balance the following equation for this reaction.
........HNO2 →……..HNO3 + .......NO + .......H2O
3HNO2 →1HNO3 + 2 NO + 1 H2O
Sodium chlorate(V) may be prepared by passing chlorine into hot aqueous sodium hydroxide.
Balance the equation for this reaction below.
…… Cl2 + …… NaOH → …… NaCl + ….NaClO3 + …H2O
3 Cl2 + 6 NaOH → 5NaCl + 1NaClO3 + 3H2O
Balance the equation below
........C3H5N3O9(l) → .......CO2(g) + ......H2O(g) + ....N2(g) +...... O2(g)
4C3H5N3O9(l) → 12CO2(g) + 10H2O(g) + 6N2(g) +1O2(g)
Balance the equation below
........B2O3 + .......C +.........Cl2 → .......BCl3 +...... CO
1B2O3 + 3C + 3Cl2 → 2BCl3 + 3CO
A student heats 5.29 g of Sr(NO3)2 and collects the gas at room temperature and pressure, RTP. 2Sr(NO3)2(s) → 2SrO(s) + 4NO2(g) + O2(g)
Calculate the volume of gas, in dm3 , obtained by the student at RTP. Molar mass of Sr(NO3)2 = 211.6 g mol –1 .
1.50dm3
•Sodium hydrogencarbonate decomposes on heating as shown by the equation below.
•2NaHCO3 → Na2CO3 + H2O + CO2
•Calculate the volume of carbon dioxide, measured at 298 K and 101 kPa, obtained by heating 0.0500 mol of sodium hydrogencarbonate.
600cm3
Calcium carbonate, CaCO3, reacts with hydrochloric acid as shown in the equation below.
CaCO3(s) +2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
7.50 × 10–3 mol CaCO3 reacts with 0.200 mol dm–3 HCl. (i) Calculate the volume, in cm3 , of 0.200 mol dm–3 HCl required to react with 7.50 × 10–3 mol CaCO3.
75 cm3
??sodium reacts with cold water.
Calculate the volume of gas produced if 3 g of sodium recats with excess water at room temperature and pressure
1.56 dm3
A salt, X, contains 16.2% by mass of magnesium, 18.9% by mass of nitrogen and 64.9% by mass of oxygen. Determine the empirical formula of X.
(Ar Mg=24, N=14 and O=16)
MgN2O6
Compound Y contains 45.9% of potassium and 16.5% of nitrogen by mass, the remainder being oxygen.
Use the data above to calculate the empirical formula of Y.
Ar K=39 , N=14, 0=16
KNO2
A chromium compound contains 28.4% of sodium and 32.1% of chromium by mass, the remainder being oxygen. Calculate the empirical formula of this compound
Ar Cr= 52 , Na=23, O=16
Na2CrO4
Compound X, which contains carbon, hydrogen and oxygen only, has 38.7% carbon and 9.68% hydrogen by mass. Calculate the empirical formula of X.
CH3O
Sodium azide is made by reacting dinitrogen monoxide gas with sodium amide (NaNH2) as shown by the equation.
2NaNH2 + N2O →NaN3 + NaOH + NH3
Calculate the mass of sodium amide needed to obtain 550 g of sodium azide, assuming there is a 95.0% yield of sodium azide.
•Give your answer to 3 significant figures.
Ar Na=23, N=14, H=1
695 grams
Lead(II) nitrate may be produced by the reaction between nitric acid and lead(II) oxide as shown by the equation below.
PbO + 2HNO3 → Pb(NO3)2 + H2O
An excess of lead(II) oxide was allowed to react with 175 cm3 of 1.50 mol dm–3 nitric acid. Calculate the maximum mass of lead(II) nitrate which could be obtained from this reaction.
43.5 grams
A student carries out a titration to find the concentration of some sulfuric acid. The student finds that 25.00 cm3 of 0.0880 mol dm–3 aqueous sodium hydroxide, NaOH, is neutralised by 17.60 cm3 of dilute sulfuric acid, H2SO4.
H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + 2H2O(l)
Calculate the concentration of sulfuric acid, H2SO4
6.25 x10-2 moldm-3
Nickel makes up 25% of the total mass of a fifty pence coin. A fifty pence coin has mass of 8.0 g.
Calculate the number of atoms of nickel in a fifty pence coin. L = 6.02 × 1023 mol–1
...........................
2.1 x1022 atoms
The carbonate of metal M has the formula M2CO3. The equation for the reaction of this carbonate with hydrochloric acid is given below.
M2CO3 + 2HCl → 2MCl + CO2 + H2O
A sample of M2CO3, of mass 0.394 g, required the addition of 21.7 cm3 of a 0.263 mol dm–3 solution of hydrochloric acid for complete reaction.
Deduce the relative molecular mass of M2CO3 and the identity of M.
138 g
Potassium
The student’s stomach contained 500 cm3 of stomach fluid with an acid concentration of 0.108 mol dm–3. The student swallowed some Milk of Magnesia containing 2.42 g Mg(OH)2.
Calculate the mass of Mg(OH)2 necessary to neutralise this stomach fluid and determine whether the student swallowed too much, too little or just the right amount
1.57 grams
too much.
When 17.471g of trioxane is burned, 10.477g of water and 25.612g of Carbon dioxide are produced. Calculate the empirical formula of the trioxane
CH2O
CH