Chapter 10 - An Introduction to Chemistry: Chemical Calculations ...

396 Chapter 10 Chemical Calculations and Chemical Equations
19. When two solutions are mixed to start a reaction, it is more convenient to measure
their _____________ than their masses.
20. Molarity (abbreviated M) is defined as moles of _____________ per liter of
_____________.
21. Conversion factors constructed from molarities can be used in stoichiometric
calculations in very much the same way conversion factors from _____________
are used. When a substance is pure, its molar mass can be used to convert back and
forth between the measurable property of _____________ and moles. When a
substance is in solution, its molarity can be used to convert between the measurable
property of _____________ and moles of solute.
Chapter
Problems
Objective 2
Objective 3
Objective 2
Objective 3
Section 10.1 Equation Stoichiometry
Section 10.2 Real-World Applications of Equation Stoichiometry
22. Because the bond between fluorine atoms in F 2 is relatively weak while the
bonds between fluorine atoms and atoms of other elements are relatively strong,
it is difficult to make diatomic fluorine, F 2 . One way it can be made is to run
an electric current through liquid hydrogen fluoride, HF. This reaction yields
hydrogen gas, H 2 , and fluorine gas, F 2 .
a. Write a complete balanced equation, including states, for this reaction.
b. Draw a picture of the reaction, using rough sketches of space-filling models
in place of the coefficients and formulas in the equation. Fluorine atoms
have a little more than twice the diameter of hydrogen atoms.
c. Write a conversion factor that could be used to convert between moles of
HF and moles of F 2 .
d. How many moles of F 2 form when one mole of HF reacts completely?
e. How many moles of HF react to yield 3.452 moles of H 2 ?
23. Hydrogen gas is used for many purposes, including the hydrogenation of
vegetable oils to make margarine. The most common industrial process for
producing hydrogen is “steam reforming,” in which methane gas, CH 4 , from
natural gas reacts with water vapor to form carbon monoxide gas and hydrogen
gas.
a. Write a complete balanced equation, including states, for this reaction.
b. Draw a picture of the reaction, using rough sketches of space-filling models
in place of the coefficients and formulas in the equation. Draw the carbon
atoms a little larger than the oxygen atoms. Both carbon and oxygen atoms
have over twice the diameter of hydrogen atoms.
c. Write a conversion factor that could be used to convert between moles of
methane and moles of hydrogen.
d. How many moles of hydrogen form when 4 moles of methane react
completely?
e. How many moles of water vapor react to yield 174.82 moles of hydrogen?