4.7: Unit 4 Practice Problems
- Page ID
- 260643
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Problem 1.
Balance the following equations:
- PCl5(s)+H2O(l)→POCl3(l)+HCl(aq)
- Cu(s)+HNO3(aq)→Cu(NO3)2(aq)+H2O(l)+NO(g)
- H2(g)+I2(s)→HI(s)
- Fe(s)+O2(g)→Fe2O3(s)
- Na(s)+H2O(l)→NaOH(aq)+H2(g)
- (NH4)2Cr2O7(s)→Cr2O3(s)+N2(g)+H2O(g)
- Answer 1
-
PCl5(s)+H2O(l)→POCl3(l)+2HCl
- Answer 2
-
3Cu(s)+8HNO3(aq)→3Cu(NO3)2(aq)+4H2O(l)+2NO(g)
- Answer 3
-
H2(g)+I2(s)→2HI(s)
- Answer 4
-
4Fe(s)+3O2(g)→2Fe2O3(s)
- Answer 5
-
2Na(s)+2H2O(l)→2NaOH(aq)+H2(g)
- Answer 6
-
(NH4)2Cr2O7(s)→Cr2O3(s)+N2(g)+4H2O(g)
Question 2.
Write the balanced chemical equation for the combustion of gaseous butane, C4H10.
Answer
-
2C4H10(g)+13O2(g)→8CO2(g)+10H2O(g)
Question 3.
What is the mass of 0.54mole of CO2?
- Answer
- \[\mathrm{0.54\: \cancel{mole} \times \dfrac{44\: g}{1\:\cancel{mole}}=24\: g}\]
Question 4.
230 grams of O is how many moles of O?
- Answer
- \[\mathrm{230\: \cancel{g} \times \dfrac{1\: mole}{16\:\cancel{g}}=14\: mole O}\]
Question 5.
What is the mass of 1.00 mole of magnesium nitrate?
- Answer
- The formula for magnesium nitrate is Mg(NO3)2 mass = (1 x 24.31) + (2 x 14.01) + (6 x 16.00) = 148 g Mg(NO3)2
Question 6.
How many atoms are on 1.76 moles of phosphorus?
- Answer
- \[\mathrm{1.76\: \cancel{mole} \times \dfrac{6.02e23\: atoms}{1\:\cancel{mole}}=1.06e24\: atoms}\] 1.06x1024atoms
Question 7.
What is the mass of 3.57x1024molecules of CaS?
- Answer
Question 8.
Automotive air bags inflate when a sample of sodium azide, NaN3, is very rapidly decomposed.
2NaN3(s)→2Na(s)+3N2(g)
If this reaction begins with only 1.46 moles of NaN3, how many moles of nitrogen gas, N2, will be produced?
- Answer
Question 9.
What mass of silver oxide, Ag2O, is required to produce 25.0 g of silver sulfadiazine, AgC10H9N4SO2, from the reaction of silver oxide and sulfadiazine?
2C10H10N4SO2+Ag2O→2AgC10H9N4SO2+H2O
- Answer
-
= 8.11 g Ag2O
Question 10.
Identify the energy graphs A and B as being for an endothermic or exothermic reaction.
A.
B.
- Answer
- A. exothermic B. endothermic