Chemical Processes and Equations Study Questions and Answers

Chemical Processes and Equations Study Questions and Answers Q: You can identify most substances by identifying their... A: Properties Q: Are Sample A and Sample B the same substance? A: No, they are different substances because one substance dissolved in water and the other substance did not dissolve in water. Q: Explain physical properties of a substance. A: The physical properties of a substance are ones that can be observed or measured without changing the substance's identity. Q: Explain chemical properties of a substance. A: Chemical properties define the ways a substance can undergo changes that form different substances. Q: Are the two nails made of the same substance? A: No, when the two nails that looked alike were left outside, only one had a change that indicated that a new substance had formed. Nail 1 rusted, while nail 2 did not rust. Q: Explain why it is important to look at several properties before drawing a conclusion on whether two substances are the same. A: Different substances may have some properties that are the same, but not all of their properties will be the same. You may need evidence about several different properties to determine whether the two substances are the same. Q: What are some examples of physical change? A: Changes such as water freezing or metal being hammered into a thinner sheet do not alter the identity of the substance. Q: What is a chemical reaction? A: Chemical reaction is the process in which the building blocks of matter—atoms—are rearranged to produce different substances. Q: What happens to atoms that make up reactants during a chemical reaction? A: During a chemical reaction, the atoms that make up the reactants regroup (or rearrange) into different particles to form products. Q: Label each image to identify the change that is taking place. Q: Some observations that are signs of a chemical reaction include... Q: Observations such as the formation of a precipitate, the production of light or heat, or a change in color suggest that a chemical reaction has taken place, but these indications are not conclusive. So what is most definitive evidence? A: Definite evidence for a chemical reaction requires proof that at least one new substance is present after the change. Q: Identify a physical change from the picture. A: Candle wax melting.