Study Island Copyright 2015 Edmentum - All rights reserved. Generation Date: 03/16/2015 Generated By: Kristina Brown 1. Edgar is stranded on an island surrounded by an ocean of salt water. He is thirsty, but he knows that it is a bad idea to drink salt water. How could Edgar separate the salt out of the salt-water mixture? A. evaporate off the water B. use a magnet to attract the salt C. use chromatography D. pour the mixture through a screen 2. What would be the best way to separate jelly beans by color? A. screening B. filtration C. sorting D. evaporation 3. Which of the following is true about mixtures and compounds? A. B. A mixture contains different substances that are not chemically combined with one another. A compound forms when different substances chemically combine to form a new substance.
Mixtures and compounds are both made of two or more different substances. C. D. all of these 4. Mario places 10 ml of water in a test tube and heats the liquid over a Bunsen burner for 2 minutes. After removing the test tube from the Bunsen burner, there are 6 ml of water left in the test tube. This experiment is a good example of a A. physical change involving phase changes. B. physical change involving chemical reactions. C. chemical change involving chemical reactions. D. chemical change involving phase changes. 5. Which of the following is a chemical change? A. an iron bar rusting B. the inflation of a car tire C. the melting of gold D. oil floating on water 6. Albert knows that blood is composed of white blood cells, red blood cells, and plasma. Each of these three components has different densities. Using this knowledge, what method could Albert use to separate out all the components of blood? A. magnetism B. filtration C. centrifuge D. evaporation 7. Iron filings could be separated from sand using. A. filtration B. a magnet C. boiling D. chromatography
8. A solution of hydrochloric acid is placed on a balance. Magnesium metal is added and the mass is recorded. The solution is stirred and the mass of the solution is recorded every 10 minutes. The following data is collected: Time (mins) Mass of Hydrochloric Acid and Magnesium (g) 0 160.0 g 10 156.5 g 20 152.0 g 30 147.5 g 40 142.5 g What does the data show is occurring? A. The hydrochloric acid and magnesium metal react to form a precipitate. B. The hydrochloric acid and magnesium metal react to form a soluble compound. C. The hydrochloric acid and magnesium metal react to form a gas. D. The hydrochloric acid and magnesium metal do not react. 9. Michael mixes two chemicals together in a beaker. The chemicals change color, and the beaker heats up quickly. What kind of change most likely occurred? A. No change occurred. B. Only a physical change occurred. C. A mixture formed. D. A chemical change occurred. 10. Which of the following is true about the mass of the reactants in a chemical reaction? A. B. C. The total mass of the reactants in a chemical reaction is conserved and will be equal to the total original mass of the products. The total mass of the reactants in a chemical reaction will be significantly more than the total mass of the products. The total mass of the reactants in a chemical reaction will never be equal to the total mass of the products. D. The total mass of the reactants in a chemical reaction will be significantly less than the
total mass of the products. Answers 1. A 2. C 3. D 4. A 5. A 6. C 7. B 8. C 9. D 10. A Explanations 1. A mixture of substances can be separated into its original substances by using its characteristic properties. For example, the best way to separate the salt out of a salt-water mixture is to evaporate off the water. This is possible because salt and water have different boiling points. Once all the water has evaporated, the dry, solid salt will be left behind. 2. Mixtures are made up of two or more substances that are not chemically combined. When mixed, the identities of the original substances stay the same. Since they are only physically combined, a mixture can be separated into its original substances by using the substances' characteristic properties. For example, jelly beans can be separated by color by sorting them into piles by hand. 3. All of these are true about mixtures and compounds. Mixtures and compounds are both made of two or more different substances. The key difference between mixtures and compounds is that a compound is a new substance that forms when other substances chemically combine. The new substance that is formed has different properties from the original substances. A mixture is simply a physical combination of two or more substances. Some of the individual properties of the original substances are retained by the mixture.
4. The experiment is a good example of a physical change involving a phase change. Initially there were 10 ml of water in the liquid state. After it was removed from the Bunsen burner, there were 6 ml still in the liquid state. So, 4 ml of water changed from a liquid state to a gas state. The phase of matter, not the structure of matter, changed. 5. A physical change alters one of the physical properties of a substance (e.g. size, shape, color, etc.), but it does not change the substance itself. A chemical change causes new substances to be formed. The new substances have different chemical properties from the original substance. An iron bar rusting is an example of a chemical change because iron reacts with oxygen to form rust. 4 Fe + 3 O 2 2 Fe 2 O 3 6. A centrifuge is a machine that separates mixtures according to the densities of the components. Magnetism separates mixtures according to their attraction to a magnet. Filtration separates particles of different sizes. And evaporation separates liquids from solids. 7. Mixtures are made up of two or more substances that are not chemically combined. When mixed, the identities of the original substances stay the same. Since they are only physically combined, a mixture can be separated into its original substances by using the substances' characteristic properties. For example, since iron is magnetic and sand is not magnetic, if a magnet is held over a dish containing a mixture of sand and iron filings, the iron filings would be attracted to the magnet, and pure sand would be left behind. 8. The data collected shows that the mass is decreasing as the reaction continues. This shows that the reaction is producing a gas, with the mass decreasing as the gas is lost from the system. 9. A chemical change occurs when the original substances (the reactants) are changed into a new substance or substances (the products). A chemical change can be indicated by a color change, gas formation, solid formation, or a temperature change. If the temperature of the chemicals rises quickly, a chemical change most likely occurred. A physical change is a change that does not change the chemical properties of the substances involved. A physical change can be the result of a temperature change, but a change in temperature does not result from a physical change. A mixture is a kind of physical change. 10. The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical or physical change it is only rearranged. Therefore, the total mass of the reactants in a chemical reaction is conserved and will be equal to the total mass of the products.