Identification of common gases：練習題

A student has a test tube containing a gas produced during the reaction of a metal with an acid. They hold a burning splint at the open end of the test tube. Which result would identify the gas as hydrogen?

When carbon dioxide is bubbled through an aqueous solution of calcium hydroxide (limewater), a specific change is observed. Which of the following correctly describes the chemical test and the positive result for carbon dioxide?

A sample of an unknown gas is tested by placing damp litmus paper into it. The student observes that the paper is bleached and turns white. Which gas is being identified, and what is the nature of the litmus paper used?

Which of the following is the correct test and result for identifying chlorine gas?

A student observes a gas being bubbled through an aqueous solution of calcium hydroxide. The solution gradually turns milky.

Name the gas produced and explain the chemical change occurring in the limewater.

A student collects a gas produced from a reaction between a metal and an acid. When a burning splint is held near the mouth of the tube, a 'squeaky pop' is heard.

Identify the gas and write a balanced symbol equation for the reaction occurring during the 'pop' test.

A chemist tests a sample of an unknown gas by holding a glowing splint at the mouth of the test tube. The splint relights.

Identify the gas and state the chemical property demonstrated by this test.

A student carries out three separate experiments to identify three different unknown gases: Gas A, Gas B, and Gas C.

a) Gas A is collected in a test tube. When a damp litmus paper is held in the mouth of the tube, the paper is bleached white. Identify Gas A. (1)

b) Gas B is bubbled through an aqueous solution of calcium hydroxide (limewater). The solution turns cloudy.
i) Identify Gas B. (1)
ii) Explain why the limewater turns cloudy, referring to the type of substance formed in the reaction. (2)

c) Gas C is tested by holding a glowing splint near the mouth of the test tube. The splint relights. Identify Gas C. (1)

d) Describe the specific test and the expected positive result used to identify hydrogen gas. (2)