6.8 CHAPTER 6. QUANTITATIVE ASPECTS OF CHEMICAL CHANGE
In one such reaction 0.74 g of O 3 reacts with 0.67 g NO.
(a) Calculate the number of moles of O 3 and of NO present atthe start of the
reaction.
(b) Identify the limitingreagent in the reaction and justify your answer.
(c) Calculate the mass of NO 2 produced from the reaction.
(DoE Exemplar Paper 2,2007)
- A learner is asked tomake 200 cm^3 of sodium hydroxide (NaOH) solution of con-
centration 0.5 mol.dm−^3.
(a) Determine the massof sodium hydroxide pellets he needs to use to do this.
(b) Using an accurate balance the learner accurately measures the correct mass of
the NaOH pellets. To the pellets he now addsexactly 200 cm^3 of pure water.
Will his solution have the correct concentration?Explain your answer.
The learner then takes300 cm^3 of a 0.1 mol.dm−^3 solution of sulphuric acid
(H 2 SO 4 ) and adds it to 200 cm^3 of a 0.5 mol.dm−^3 solution of NaOH at 25^0 C.
(c) Write down a balanced equation for the reaction which takes place when these
two solutions are mixed.
(d) Calculate the number of moles of H 2 SO 4 which were added to the NaOH solu-
tion.
(e) Is the number of moles of H 2 SO 4 calculated in the previous question enough
to fully neutralise the NaOH solution? Supportyour answer by showingall the
relevant calculations.
(IEB Paper 2, 2004)
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