# Problem: A common way to make hydrogen gas in the laboratory is to place a metal such as zinc in hydrochloric acid. The hydrochloric acid reacts with the metal to produce hydrogen gas, which is then collected over water. Suppose a student carries out this reaction and collects a total of 169.7 mL of gas at a pressure of 749 mmHg and a temperature of 25°C. What mass of hydrogen gas (in mg) does the student collect? Express your answer using three significant figures.

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For problems that involve collecting gas over water, we should note that the total pressure is the sum of the partial pressure of the gas and water. We have to look for the value for the partial pressure of water at a certain temperature from literature (books/tables).

90% (176 ratings) ###### Problem Details

A common way to make hydrogen gas in the laboratory is to place a metal such as zinc in hydrochloric acid. The hydrochloric acid reacts with the metal to produce hydrogen gas, which is then collected over water. Suppose a student carries out this reaction and collects a total of 169.7 mL of gas at a pressure of 749 mmHg and a temperature of 25°C. What mass of hydrogen gas (in mg) does the student collect? Express your answer using three significant figures.

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Collecting Gas Over Water concept. If you need more Collecting Gas Over Water practice, you can also practice Collecting Gas Over Water practice problems.

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Based on our data, we think this problem is relevant for Professor Xue's class at GSU.