Question

1. choose the best answer. use significant figures.

use the combined gas law to solve for the initial volume.
$p_1 = 700.0\\ mmhg$
$v_1 = ?$
$t_1 = 100.0\\ ^\circ c$
$p_2 = 900.00\\ mmhg$
$v_2 = 225\\ ml$
$t_2 = 150\\ ^\circ c$
193 ml
328 ml
255 ml

Explanation:

Step1: Convert temp to Kelvin

$T_1 = 100.0 + 273.15 = 373.15\ \text{K}$
$T_2 = 150 + 273.15 = 423.15\ \text{K}$

Step2: Rearrange combined gas law

The combined gas law is $\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$. Rearranging for $V_1$ gives:
$V_1 = \frac{P_2V_2T_1}{P_1T_2}$

Step3: Substitute values into formula

$V_1 = \frac{900.00\ \text{mmHg} \times 225\ \text{mL} \times 373.15\ \text{K}}{700.0\ \text{mmHg} \times 423.15\ \text{K}}$

Step4: Calculate and apply sig figs

First compute the numerator: $900.00 \times 225 \times 373.15 = 900.00 \times 83958.75 = 75562875$
Then the denominator: $700.0 \times 423.15 = 296205$
$V_1 = \frac{75562875}{296205} \approx 255.1\ \text{mL}$. Round to 3 significant figures (matching $V_2$ and $T_2$ with the least sig figs).

Answer:

255 mL