C5 - Measuring Gases and Gas Volumes Flashcards
How do you measure gas using a syringe?
A gas syringe is a gas-tight glass syringe. The syringe is connected to the reaction container by tubing. As the reaction occurs, gas fills the gas syringe and pushes the plunger out. Graduations on the side show the volume of gas contained in the gas syringe.
In what other way can gas be measured?
Gases can also be collected over water in an upturned measuring cylinder. This is filled with water, then turned upside down in a trough of water. Air pressure keeps the water inside the cylinder. A delivery tube is led from the reaction container and into the mouth of the measuring cylinder. As the reaction occurs, gas fills the measuring cylinder and pushes the water out. Graduations on the side show the volume of gas contained. The same method, called upward displacement, also works using an upturned burette.
What gases can be measured with a syringe and with upwards displacement?
Gas syringes can be used to measure the volume of any gas, including carbon dioxide, hydrogen, and oxygen.
Upward displacement is only accurate if the gas is not very soluble in water. It does not so work well for soluble gases such as carbon dioxide.
How can gas be measured using a balance?
The balance has to have a suitable resolution, such as ±0.01 g, to be able to make precise readings. The reaction container, with its contents, is placed on the balance. As the reaction takes place, the gas escapes and the total mass of the container and its contents goes down. The difference in mass is due to the gas that has escaped.
What is the world and symbol reaction for the reaction between magnesium and hydrochloric acid?
Magnesium + hydrochloric acid -> magnesium chloride + hydrogen
Mg + 2HCl -> MgCl2 + H2
What is one mole of any gas?
One mole of any gas occupies the same volume at room temperature and pressure, rtp. This molar volume is 24 dm3.
How do you work out amount of gas?
Amount = volume of gas at rtp / molar volume at rtp (24)
