A sample of Oxygen gas occupies a volume of 1.50 L at a pressure of 735 mmHg and a temperature of 25 celsius. What volume will it occupy, in liters, if the pressure is increased to 70 mmHg with no change in temperature?
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A sample of Oxygen gas occupies a volume of 1.50 L at a pressure of 735 mmHg and a temperature of 25 celsius. What volume will it occupy, in liters, if the pressure is increased to 70 mmHg with no change in temperature?
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Combined Gas Law
P1V1/T1 = P2V2/T2
where in, P1 = 1st given pressure
V1 = 1st given volume
T1 = 1st given temperature
P2 = 2nd given pressure
V2 = 2nd given volume
T2 = 2nd given temperature
Given: P1 = 735mmHg
V1 = 1.50L
T1 = 298.15K
P2 = 70mmHg
T2 = 273.15K
Note: Dealing with Temperature in (each from the) Gas Law, must always be in Kelvin, that's why conversion of °C to K was applied.
°C ----> K
T1 = 25°C + 273.15 = 298.15K
T2 = 0°C + 273.15 = 273.15K
the problem said that T2 doesn't change that's why it's value is 0°C
Unknown: V2 = ?
Formula: V2 = P1V1T2/P2T1
Note: Using the formula of Combined Gas Law we can get the formula we need to find the Volume by following these steps:
• original formula: P1V1/T1 = P2V2/T2
• apply cross-multiplication:
P1 × V1 × T2 = P2 × V2 × T1
• divide both sides with corresponding terms to cancel out like terms, so the one we need will remain which is V2.
P1V1T2 / P2T1 = P2V2T1 / P2T1
V2 = P1V1T2/P2T1
• final formula: V2 = P1V1T2/P2T1
Solution:
V2 = P1V1T2/P2T1
= (735mmHg)(1.50L)(273.15K) / (70mmHg)(298.15K)
= 301147.875mmHg•L•K / 20870.5mmHg•K
= 14.43L
Final Answer: 14.43L