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Why did you not collect the first few bubbles of gas?

Why did you not collect the first few bubbles of gas?

Answer: (i) The first few bubbles of hydrogen gas should not be collected since they contain air mixed with the gas. Air mixed with hydrogen forms an explosive mixture.

Why is hydrogen gas collected by water displacement method?

Hydrogen is collected by downward displacement of water as it is less denser than water. Hence it comes out at the surface of water . It is insoluble in water so it does not dissolve in water. In case of displacement with air, it is not possible even if hydrogen is lighter than air (14.5 times lighter than air).

Why do the hydrogen gas bubbles rise in the water?

In hydrogen bubble method, bubble plume generation was dependent on the ion strength of the solvent. Bubble diameter change was derived from the diffusion of dissolved gas. In water electrolysis, the bubble diameter increased after bubble generation for both hydrogen and oxygen because of oversaturation of the gas.

What properties must a gas have to make it suitable for collecting over water?

The method of collecting a gas produced by a chemical reaction will depend on its solubility and its density. It is the best method of collecting a gas so long as the gas is insoluble or slightly soluble in water.

What are the sources of error when measuring the volume of gas?

Measurements of volume of gas collected are subject to experimental error, which could be because: some gas may escape before it can be collected in the upturned measuring cylinder. the resolution of the measuring cylinders may be different, causing different values for the volume to be recorded.

Why is methane collected by downward displacement of water?

Methane gas is collected by downward displacement of water Because it is insoluble in water and is lighter than air.

Why is oxygen collected by downward displacement of water?

Oxygen is collected by the downward displacement of water because it is only slightly soluble in water and is less dense than water. It cannot be collected by downward displacement of air since oxygen is slightly heavier than air and also it will get mixed with other gases in the air.

Why are more bubbles seen near cathode in electrolysis of water?

During the electrolysis of water why do you observe more Bubbles at the cathode than the anode. During electrolysis of water more bubbles are produced at cathode because at cathode reduction reaction takes place, producing hydrogen gas. and at anode water is oxidized.

Why are gas bubbles released at electrodes?

References (84) Bubbles coalesce into large bubbles on the surfaces and then detach from the electrode surfaces at a larger bubble diameters because gravity, buoyancy and hydrodynamic drag forces exceed the surface tension. In opposition, surface tension acts to hold bubbles on electrode surfaces.

Why gases are collected over water?

Gases that do not react with water or dissolve in water are often collected over water (see p. Dalton’s Law is useful in dealing with gases collected over water because the measured pressure is the sum of the partial pressure of the gas and the partial pressure of the water vapour (the vapour pressure of water).

What does Graham’s law say?

the principle that at a given temperature and pressure the rate of diffusion of a gas is inversely proportional to the square root of its density.