A 1.25-g sample of CO2 is contained in a 750 .-mL flask at 22.5^∘ C . What is the pressure of th

A 1.25-g sample of CO2 is contained in a 750 .-mL flask at...

Key Concepts

Unit Conversions in Gas Calculations

Accurate gas calculations require proper unit conversions to ensure consistency, especially when using the ideal gas law. This involves converting temperature from degrees Celsius to Kelvin and adjusting volume measurements to liters, which is crucial for obtaining correct results in thermodynamic equations.

Ideal Gas Law

The ideal gas law is a fundamental equation in physical chemistry that relates the pressure, volume, temperature, and number of moles of a gas. Its expression, PV = nRT, allows for solving problems involving any one of these variables provided the others are known, under the assumption that the gas behaves ideally with negligible interactions between its particles.

Mole Concept and Molar Mass

The mole concept connects the mass of a substance to the number of particles it contains, using the substance's molar mass. This conversion from a mass measurement to moles is essential when employing the ideal gas law, as it provides the necessary quantity of gas in moles for the calculation.

Transcript

00:01 We have here a sample of carbon dioxide host mass is 1 .25 grams of carbon dioxide.

00:17 And this sample is contained in a volume of 750 ml and is at a temperature of 22 .5 .m.

00:32 And is at a temperature of 22 .5.

00:38 Celsius.

00:40 We need to determine the pressure of this sample, gas sample of carbon dioxide.

00:50 So we are going to apply the equation of the ideal gas.

00:55 Pressure times volume equals the number of moles times the constant of the ideal gas times the temperature in kelvin, in degrees kelvin.

01:12 So we need to find the pressure.

01:15 We have the volume.

01:18 We have the amount of the gas, so the mass of the gas, but we don't have the most of the gas.

01:25 So we need to convert these grams to moles.

01:29 Obviously, we have the concern of the ideal gas and we have the temperature that we need to convert to decrease kelvin.

01:37 So let's do the conversions first before we do the substitution and then solving for real.

01:43 Pressure so one one point 25 grams of carbon dioxide must be divided by the molar mass of carbon dioxide the molar mass of carbon dioxide is one times twelve the atomic weight of carbon plus that's 12 plus two times 16 the atomic weight of oxygen and this is grams per mole this is how we convert these grams to moles the grams will cancel and we're gonna have mole which is in the numerator of a numerator in the denominator of a denominator and therefore it's gonna be a become a numerator so we need to divide 1 .25 by 44 12 plus 32 is 44 so 1 .25 divided by 44 and we get 0 .084 moles of carbon dioxide.

03:07 Now we convert the temperature.

03:10 The temperature in kelvin's so this is n number of moles.

03:16 The temperature in kelvin's will be the temperature in celsius plus 273 and the answer is to 22 .5 plus 273 is 22 .5 plus 273 is 295 .5 degrees kelvin.

03:44 Okay...

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