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The concentration of ethanoic acid in a sample of vinegar is determined by titration against a solution of sodium hydroxide of known concentration. Which procedure is most likely to produce a systematic error in the calculated concentration of the acid? A.…
A fixed amount of magnesium reacts with hydrochloric acid, which is added in increasing amounts. After each addition the reaction is allowed to finish. Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) Which graph shows how the amount of hydrogen formed changes…
In a precipitation reaction, further portions of the excess reactant are added after the limiting reactant has been completely consumed. Which graph shows how the amount of precipitate formed depends on the amount of excess reactant added? A. Graph A B. Graph…
Which data can be used to determine the empirical formula of an unknown hydrocarbon? A. The enthalpy change of combustion of the hydrocarbon B. The boiling point and density of the hydrocarbon C. The molar mass of the hydrocarbon D. The masses of carbon…
Which data are sufficient to determine the empirical formula of an oxide of a known metal M? A. The density and the colour of the oxide B. The enthalpy change of formation and the melting point of the oxide C. The mass of M used and the mass of oxide formed D.…
0.20 mol of ammonium hydrogencarbonate is heated gently until all of the solid has decomposed. NH4HCO3(s) → NH3(g) + H2O(g) + CO2(g) How many moles of gas are produced? A. 0.20 B. 0.40 C. 0.60 D. 0.80
(i) Write a balanced equation for the reaction of calcium with oxygen to form calcium oxide. (ii) State the block of the periodic table in which calcium is located. (iii) Calcium oxide is a basic oxide. Identify an element in period 3 that forms an amphoteric…
In an experiment, calcium turnings were heated strongly in a crucible with a lid. The following data were recorded: (i) Calculate the amount of calcium, in mol, that was used. (ii) Determine the percentage uncertainty in the final mass of product. (iii) Assume…
A student heated 3.492 g of calcium turnings in a crucible with a lid and obtained 4.490 g of solid product. If the product is assumed to be calcium oxide only, the percentage yield is 92 %. (i) Evaluate whether the formation of calcium nitride, rather than…
The presence of calcium nitride in the product can be demonstrated by adding water. The nitride is hydrolysed to form calcium hydroxide and ammonia. (i) Calculate coefficients that balance the equation for the reaction: __ Ca3N2(s) + __ H2O(l) →…