6.2. Rate of reaction
A subsection of Chemistry, 0620, through 6. Chemical reactions
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20.0 g of small lumps of calcium carbonate and 40 cm3 of hydrochloric acid, concentration 2.0 mol / dm3, were placed in a fl ask on a top pan balance. The mass of the fl ask and contents was recorded every minute. cotton wool to prevent drops of acid spray escaping flask 40 cm3 of hydrochloric acid, 2.0 mol / dm3 20.0 g of small lumps of calcium carbonate balance The mass of carbon dioxide given off was plotted against time. time mass of carbon dioxide CaCO3+ 2HCl  CaCl 2+ H2O+ CO2In all the experiments mentioned in this question, the calcium carbonate was in excess. Explain how you could determine the mass of carbon dioxide given off in the fi rst fi ve minutes. Label the graph F where the reaction rate is the fastest, S where it is slowing down and 0 where the rate is zero. Explain how the shape of the graph shows where the rate is fastest, where it is slowing down and where the rate is zero. Sketch on the same graph, the line which would have been obtained if 20.0 g of small lumps of calcium carbonate and 80 cm3 of hydrochloric acid, concentration 1.0 mol / dm3, had been used. Explain in terms of collisions between reacting particles each of the following. The reaction rate would be slower if 20.0 g of larger lumps of calcium carbonate and 40 cm3 of hydrochloric acid, concentration 2.0 mol / dm3, were used. The reaction rate would be faster if the experiment was carried out at a higher temperature. Calculate the maximum mass of carbon dioxide given off when 20.0 g of small lumps of calcium carbonate react with 40 cm3 of hydrochloric acid, concentration 2.0 mol / dm3. CaCO3+ 2HCl  CaCl 2+ H2O+ CO2number of moles of HCl used = mass of carbon dioxide = g
0620_w13_qp_31
THEORY
2013
Paper 3, Variant 1
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