Which of the changes listed below would shift the following reaction to the right? The reaction is: $\ce{4HCl(g) + O_2(g) -> 2Cl2(g) + 2H2O(g)}$

• a) addition of Cl$_2$
• b) removal of O$_2$
• c) increase in pressure
• d) decrease in pressure

Allicin is the compound responsible for the characteristic smell of garlic. An analysis of the compound gives the following percent composition by mass: C, 44.4 percent; H, 6.21 percent; S, 39.5 percent; and O, 9.86 percent. Calculate its empirical formula. What is its molecular formula given that its molar mass is about 162g?

All the substances listed here are fertilizers that contribute nitrogen to the soil. Which of these is the richest source of nitrogen on a mass percentage basis?

$$\\$$

(a)

$$\text{Urea}\;\mathrm{[(NH_2)_2CO]}$$

(b)

$$\text{Ammonium nitrate}\;\mathrm{(NH_4NO_3)}$$

(c)

$$\text{Guanidine}\;\mathrm{[HNC(NH_2)_2]}$$

(d)

$$\text{Ammonia}\;\mathrm{(NH_3)}$$

Potassium superoxide $\left(\mathrm{KO}_2\right)$ is a useful source of oxygen employed in breathing equipment. Exhaled air contains moisture, which reacts with $\mathrm{KO}_2$ to produce oxygen gas. (The other products are potassium hydroxide and hydrogen peroxide.) (a) Write an equation for the reaction. (b) Calculate the pressure at which oxygen gas stored at $20^{\circ} \mathrm{C}$ would have the same density as the oxygen gas provided by $\mathrm{KO}_2$. The density of $\mathrm{KO}_2$ at $20^{\circ} \mathrm{C}$ is $2.15 \mathrm{~g} / \mathrm{cm}^3$. Comment on your result.

The root-mean-square speed of a certain gaseous oxide is 493 m/s at 20 degree C. What is the molecular formula of the compound?

Nitrogen forms several gaseous oxides. One of them has a density of 1.33 g/L measured at 764 mmHg and 150 °C. Write the formula of the compound.

Air entering the lungs ends up in tiny sacs called alveoli. It is from the alveoli that oxygen diffuses into the blood. The average radius of the alveoli is 0.0050 cm and the air inside contains 14 percent oxygen. Assuming that the pressure in the alveoli is 1.0 atm and the temperature is 37 degree C, calculate the number of oxygen molecules in one of the alveoli.

In 1995 a man suffocated as he walked by an abandoned mine in England. At that moment there was a sharp drop in atmospheric pressure due to a change in the weather. Suggest what might have caused the man’s death.

Commercially, compressed oxygen is sold in metal cylinders. If a 120-L cylinder is filled with oxygen to a pressure of 132 atm at 22 degree C, what is the mass (in grams) of O2 present? How many liters of O2 gas at 1.00 atm and 22 degree C could the cylinder produce? (Assume ideal behavior.)

The following procedure is a simple though somewhat crude way to measure the molar mass of a gas. A liquid of mass 0.0184 g is introduced into a syringe like the one shown here by injection through the rubber tip using a hypodermic needle. The syringe is then transferred to a temperature bath heated to 45 degree C, and the liquid vaporizes. The final volume of the vapor (measured by the outward movement of the plunger) is 5.58 mL and the atmospheric pressure is 760 mmHg. Given that the compound’s empirical formula is CH2, determine the molar mass of the compound.

The volume of a sample of pure HCl gas was 189 mL at 25 degree C and 108 mmHg. It was completely dissolved in about 60 mL of water and titrated with an NaOH solution; 15.7 mL of the NaOH solution were required to neutralize the HCl. Calculate the molarity of the NaOH solution.

A sample of zinc metal reacts completely with an excess of hydrochloric acid:

$$\begin{align*} \mathrm{Zn}(s)+2\;\mathrm{HCl}(aq)&\rightarrow\mathrm{ZnCl_2}(aq)+\mathrm{H_2}(g) \end{align*}$$

The hydrogen gas produced is collected over water at 25.0 °C using an arrangement similar to that shown in Figure 10.14(a). The volume of the gas is 7.80 L, and the pressure is 0.980 atm. Calculate the amount of zinc metal in grams consumed in the reaction. (Vapor pressure of water at 25 °C = 23.8 mmHg.)

A compound of P and F was analyzed as follows: Heating 0.2324 g of the compound in a 378-cm3 container turned all of it to gas, which had a pressure of 97.3 mmHg at 77 degree C. Then the gas was mixed with calcium chloride solution, which turned all of the F to 0.2631 g of CaF2. Determine the molecular formula of the compound.

Assuming that air contains 78 percent N2, 21 percent O2, and 1 percent Ar, all by volume, how many molecules of each type of gas are present in 1.0 L of air at STP?