iran-konkur 2020 Q212

iran-konkur · Other · konkur-riazi_1399_specialized_old-curriculum Not Maths
212 -- Based on the following reactions, if $630$ grams of nitric acid with $80\%$ purity reacts with copper metal, how many moles of copper(II) nitrate are formed and the gas $\text{NO}_2$ produced in this reaction combines with oxygen gas to form $\text{NO}$ -- at STP conditions, what total volume (in liters) does it occupy? (Choose the answers from right to left.)
$$(\text{H}=1,\ \text{N}=14,\ \text{O}=16\ \text{: g.mol}^{-1})$$
$$\begin{cases} \text{HNO}_3(\text{aq}) + \text{Cu}(\text{s}) \rightarrow \text{Cu(NO}_3)_2(\text{aq}) + \text{NO}_2(\text{g}) + \text{H}_2\text{O}(\text{l}) & \text{(balanced reaction)} \\ \text{NO}_2(\text{g}) + \text{O}_2(\text{g}) \xrightarrow{\text{sunlight}} \text{NO}(\text{g}) + \text{O}_3(\text{g}) \end{cases}$$
  1. [(1)] $67.2\ ,\ 2$
  2. [(2)] $67.2\ ,\ 4$
  3. [(3)] $89.6\ ,\ 2$
  4. [(4)] $89.6\ ,\ 4$

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\textbf{212 -- Based on the following reactions, if $630$ grams of nitric acid with $80\%$ purity reacts with copper metal, how many moles of copper(II) nitrate are formed and the gas $\text{NO}_2$ produced in this reaction combines with oxygen gas to form $\text{NO}$ -- at STP conditions, what total volume (in liters) does it occupy? (Choose the answers from right to left.)}

$$(\text{H}=1,\ \text{N}=14,\ \text{O}=16\ \text{: g.mol}^{-1})$$

$$\begin{cases} \text{HNO}_3(\text{aq}) + \text{Cu}(\text{s}) \rightarrow \text{Cu(NO}_3)_2(\text{aq}) + \text{NO}_2(\text{g}) + \text{H}_2\text{O}(\text{l}) & \text{(balanced reaction)} \\ \text{NO}_2(\text{g}) + \text{O}_2(\text{g}) \xrightarrow{\text{sunlight}} \text{NO}(\text{g}) + \text{O}_3(\text{g}) \end{cases}$$

\begin{enumerate}
\item[(1)] $67.2\ ,\ 2$
\item[(2)] $67.2\ ,\ 4$
\item[(3)] $89.6\ ,\ 2$
\item[(4)] $89.6\ ,\ 4$
\end{enumerate}

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