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# STP Calculator

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Standard temperature and pressure abbreviated as STP are the set of standard conditions for performing a comparison between different data sets. Standard temperature and pressure defined by IUPAC is temperature of $0^{\circ}$ Celsius and a pressure of 1 atm pressure. Usually, STP is used to estimate gas density and volume.

STP Calculator calculates the volume and moles of a gas by using the following formula,
Volume at STP = Volume $\times$ $(\frac{273.15}{Temperature})$ $\times$ $(\frac{Pressure}{760})$

Moles at STP = $\frac{Volume \ at \ STP}{22.4}$
Where, volume, temperature and pressure of the gas is in liters, Kelvin and Torr.

## Steps

Step 1 : Put down the data from the given question.

Step 2 : Plug in the data values into the given formula and find the appropriate value according to the problem.

Volume at STP = $Volume \times$ $(\frac{273.15}{Temperature})$ $\times$ $(\frac{Pressure}{760})$

Moles at STP = $\frac{Volume \ at \ STP}{22.4}$

## Problems

Given below are some of the problems based on Standard temperature and pressure.

### Solved Examples

Question 1: 50 L of gas was collected at 640 mm Hg pressure and 15$^{\circ}$. Calculates its volume and moles at STP.
Solution:

Step 1 : Given : Volume = 50 L,
Pressure = 640 mm Hg = 640 torr,
Temperature = 15$^{\circ}$ = 288.15 Kelvin

Step 2 : Volume at STP = $Volume \times$ $(\frac{273.15}{Temperature})$ $(\frac{Pressure}{760})$

Volume at STP = $50 \times$ $(\frac{273.15}{288.15})$ $(\frac{640}{760})$

Volume at STP = 39.913

Similarly,
Moles at STP = $\frac{Volume \ at \ STP}{22.4}$

Moles at STP = $\frac{39.913}{22.4}$

Moles at STP = 1.7818

Question 2: At 24.2$^{\circ}$ temperature and 780 torr, a gas has a volume of 0.35 L. Estimate its volume at STP.
Solution:

Step 1 : Given : Volume = 0.35 L,
Pressure = 780 torr,
Temperature = 24.2$^{\circ}$ = 297.35 Kelvin

Step 2 : Volume at STP = $Volume \times$ $(\frac{273.15}{Temperature})$ $(\frac{Pressure}{760})$

Volume at STP = $0.35 \times$ $(\frac{273.15}{297.35})$ $(\frac{780}{760})$

Volume at STP = 0.32998