Answer
(a)
The pressure of this gas is equal to 832 mmHg.
(b)
The pressure of this other gas is equal to 718 mmHg.
Work Step by Step
(a)
1. Write the expression
$$P_{gas} = P_{Hg} + P_{atm}$$
2. Reading the difference of height between the fluids, we get around 7 cm, which is equal to 70 mm:
$$P_{Hg} \approx 70. \space mmHg$$
3. Calculate the pressure of the gas:
$$P_{gas} = 70. \space mmHg + 762.4 \space mmHg = 832 \space mmHg$$
(b) Repeat the steps:
1. Now, since the difference 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 4.4 cm, which is equal to 44 mm:
$$P_{Hg} \approx 44 \space mmHg$$
3. Calculate the pressure of the gas:
$$P_{gas} = 762.4 \space mmHg - 44 \space mmHg = 718 \space mmHg$$
