\(\ce{CO2}\) can react in the air with water to form carbonic acid, \(\ce{H2CO3}\), according to the following chemical equation \(\ce{CO2(g) + H2O(l) \rightarrow H2CO3(aq)} \) Carbonic acid can then react with \(\ce{NaOH}\) as follows \(\ce{2NaOH(aq) + H2CO3(aq) \rightarrow Na2CO3(aq) + 2H2O(l)}\) A 10.00 L container is completely filled with a freshly made 0.1000 mol L\(^{-1}\) \(\ce{NaOH}\) solution. During a Chemistry class, 9.90 L of the solution is used and air enters the empty space above the remaining solution before the container is completely sealed off from the outside air. The container is then opened. Air enters the container at 101.3 kPa and 21.5 °C. Assume that the concentration of \(\ce{CO2}\) in the air is 0.0400% (v/v). --- 4 WORK AREA LINES (style=lined) --- --- 2 WORK AREA LINES (style=lined) --- --- 5 WORK AREA LINES (style=lined) ---
CHEMISTRY, M2 2006 HSC 18
A student studying the mass change that occurs during fermentation added glucose, water and yeast to a flask and stoppered the flask with some cotton wool.
The student measured the mass of the flask daily for seven days. The table shows the data collected.
\begin{array} {|c|c|}
\hline
\rule{0pt}{2.5ex}\ \ \ \textit{Day}\ \ \ \rule[-1ex]{0pt}{0pt} & \ \ \textit{Mass}\ \text{(g)}\ \ \\
\hline
\rule{0pt}{2.5ex} 1 \rule[-1ex]{0pt}{0pt} & 381.05\\
\hline
\rule{0pt}{2.5ex} 2 \rule[-1ex]{0pt}{0pt} & 376.96\\
\hline
\rule{0pt}{2.5ex} 3 \rule[-1ex]{0pt}{0pt} & 373.42\\
\hline
\rule{0pt}{2.5ex} 4 \rule[-1ex]{0pt}{0pt} & 370.44\\
\hline
\rule{0pt}{2.5ex} 5 \rule[-1ex]{0pt}{0pt} & 370.42\\
\hline
\rule{0pt}{2.5ex} 6 \rule[-1ex]{0pt}{0pt} & 370.40\\
\hline
\rule{0pt}{2.5ex} 7 \rule[-1ex]{0pt}{0pt} & 370.39\\
\hline
\end{array}
- Calculate the moles of \(\ce{CO2}\) released between days 1 and 7. (1 mark)
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- Calculate the mass of glucose that underwent fermentation between days 1 and 7. Include a balanced chemical equation in your answer. (3 marks)
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CHEMISTRY, M2 2009 HSC 22
The nitrogen content of bread was determined using the following procedure:
-
- A sample of bread weighing 2.80 g was analysed.
- The nitrogen in the sample was converted into ammonia.
- The ammonia was collected in 50.0 mL of 0.125 mol L\(^{-1}\) hydrochloric acid. All of the ammonia was neutralised, leaving an excess of hydrochloric acid.
- The excess hydrochloric acid was titrated with 23.30 mL of 0.116 mol L\(^{-1}\) sodium hydroxide solution.
- Write balanced equations for the TWO reactions involving hydrochloric acid. (2 marks)
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- Calculate the moles of excess hydrochloric acid. (1 mark)
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- Calculate the moles of ammonia. (2 marks)
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- Calculate the percentage by mass of nitrogen in the bread. (2 marks)
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CHEMISTRY, M2 2013 HSC 4 MC
Butan-1-ol burns in oxygen according to the following equation.
\(\ce{C4H9OH(l)} + \ce{6O2(g)} \rightarrow \ce{4CO2(g)} + \ce{5H2O(l)} \)
How many moles of carbon dioxide would form if two moles of butan-1-ol were burnt in excess oxygen?
- 2
- 4
- 8
- 10