Mixtures and compounds ：練習問題

Which of the following statements best describes the formation of a mixture?

Which of the following chemical equations correctly represents the balanced reaction between hydrogen gas and chlorine gas to form hydrogen chloride?

A pure substance X is a colorless gas. When X is passed through a high-voltage spark, it decomposes into two different gases, Y and Z, in a fixed volume ratio of 2:1. Gas Y burns with a 'pop' sound, and gas Z relights a glowing splint. Which of the following is the most accurate classification of substance X and the nature of this change?

Based on the study of matter, which of the following substances found in nature is classified as a mixture?

A student is comparing Sample A (distilled water) and Sample B (air). Which of the following correctly identifies these substances based on their composition?

When carbon powder is mixed with iron filings, they can be separated easily with a magnet. However, when they are heated strongly to form a new substance, a magnet can no longer separate the carbon. Based on this observation, classify the new substance formed and state the type of change that occurred.

A student is given a solid mixture of sand and table salt. Describe the sequence of steps required to separate and recover both substances in their solid forms.

Sulfur powder (a yellow solid) reacts with powdered zinc (a grey metal) when heated, forming a new white solid compound, zinc sulfide ($$ZnS$$).
a) Write a balanced chemical equation for this reaction.
b) Explain one fundamental difference between the properties of zinc sulfide ($$ZnS$$) and its constituent elements, sulfur and zinc, and justify why this difference exists.

Matter is classified into three main types: elements, compounds, and mixtures. Consider three common substances: pure Iron metal (Fe), pure Water (\(H_2O\)), and Air.

(a) Define the following terms based on their composition and bonding:

(b) Based on your definitions above, classify each of the following substances into one of the three categories (Element, Compound, or Mixture):

A chemist prepares a flask containing Carbon powder (C) and Oxygen gas ( \(O_2\) ). The investigation is carried out in two distinct scenarios:

Scenario X: The flask is sealed and allowed to stand at room temperature. The contents remain separate Carbon powder and Oxygen gas.

Scenario Y: The carbon powder is ignited inside the flask, leading to a chemical reaction that consumes all the carbon and a portion of the oxygen, forming Carbon Dioxide ( \(CO_2\) ).

(a) Classify the contents of the flask in Scenario X and the resulting substance in Scenario Y (Carbon Dioxide) as either an Element, Compound, or Mixture. (2 marks)

(b) In Scenario Y, 12 g of Carbon completely reacts with 32 g of Oxygen. According to the Law of Conservation of Mass, what is the mass of the Carbon Dioxide produced? If 12 g of Carbon were mixed with 40 g of Oxygen in Scenario X, what is the total mass of the contents? (2 marks)

(c) Explain the difference between Scenario X and Scenario Y in terms of the chemical bonding between their components and why this affects how easily they can be separated. (1 mark)