## Chemistry: Molecular Approach (4th Edition)

(a) $$728 \space mmHg$$ (b) $$817 \space mmHg$$
(a) 1. Since the difference of height is negative, we write the expression as: $$P_{gas} = P_{atm} - P_{Hg}$$ 2. Reading the difference of height between the fluids, we get around 2.3 cm, which is equal to 23 mm: $$P_{Hg} \approx 23 \space mmHg$$ 3. Calculate the pressure of the gas: $$P_{gas} = 751.5 \space mmHg - 23 \space mmHg = 728 \space mmHg$$ (b) 1. Write the expression $$P_{gas} = P_{Hg} + P_{atm}$$ 2. Reading the difference of height between the fluids, we get around 6.6 cm, which is equal to 66 mm: $$P_{Hg} \approx 66 \space mmHg$$ 3. Calculate the pressure of the gas: $$P_{gas} = 66 \space mmHg + 751.5 \space mmHg = 817 \space mmHg$$