32. A chemical change affects the composition of matter because once a chemical change takes place the composition of the matter is changed, if the composition is not changed at all it is not a chemical change.
33. Four possible clues that a chemical change has taken place are transfer of energy, change in color, the production of gas, or formation of a precipitate which is a solid that forms and solids out of a liquid.
34. Compare In a chemical reaction, the mass of the products is always equal to he mass of the reactants, for example the mass of a log will be equal to the mass of all the snake and ash made by burning the log.
35. The main difference between physical changes and chemical changes is a physical change does not change the composition of the matter, it just changes forms. In a chemical change the composition of the product is changed.
36. Classify the following changes as physical or chemical changes.
a. Water boiling would be a physical change.
b. Table salt dissolves in water would be a physical change.
c. Milk turning sour would be a chemical change.
d. A metal rusting would be a chemical change.
41. Two physical properties that could be used to distinguish between water and ethanol is that water boils at 100 degrees centigrade and ethanol boils at 78.3 degrees centigrade. Also ethanol freezes at -174.6 degrees Fahrenheit and water freezes at 32 degrees Fahrenheit.
42. One physical property that could not be used to distinguish chlorine from oxygen is that both chlorine and oxygen are gases at room temperature.
43. What is the physical state of each of these materials at room temperature?
a. Gold's physical state at room temperature is solid
b. Gasoline's physical state at room temperature is liquid
c. Oxygen's physical state at room temperature is gas
d. Neon's physical state at room temperature is gas
e. Olive oil's physical state at room temperature is liquid
f. Sulfur's physical state at room temperature is solid
g. Mercury's physical state at room temperature is liquid
44. Fingernail-polish remover (mostly acetone) is a liquid at room temperature. Acetone in the gaseous state is a vapor because a vapor is the gaseous state of something that is normally a solid or a liquid and nail polish remover is normally a liquid. A gas is something that is usually always a gas.
50. Classify each of the following as a homogeneous or heterogeneous mixture.
a. Chocolate-chip ice cream would be classified as a heterogeneous mixture
b. Green ink would be classified as a homogeneous mixture
c. Cake batter would be classified as a heterogeneous mixture
d. Cooking oil would be classified as a homogeneous mixture
e. Granite rock would be classified as a heterogeneous mixture
f. Salt water would be classified as a heterogeneous mixture
g. Paint would be classified as a homogeneous mixture
h. A silver ring would be classified as a homogeneous mixture
54. Describe the relationship between the three items in each of the following groups. Identify each item as an element, compound, or mixture.
a. Hydrogen, oxygen, are both elements and water is a compound made from the elements hydrogen and oxygen
b. Nitrogen and oxygen, are elements and air is a mixture of both nitrogen and oxygen.
c. Sodium and chlorine are both elements and table salt is a compound of both sodium and chlorine
d. Carbon is an element and water is a compound and together they can make the mixture of table sugar.
60. Classify each of the following as a physical or chemical change. For any chemical change, list at least one clue to support your answer.
a. A copper wire being bent is a physical change because the chemical makeup is not being changed, only the physical appearance.
b. Charcoal burns in a grill is a chemical because the gas bonds to other elements to form a new substance, it is also irreversible.
c. Bread dough rises when yeast is added is a chemical change because the substance is changed and can't be reversed. It may be changed physical also but it's a result of a physical change.
d. Sugar dissolves in water is a physical change because the compounds are not bonding to creat new substances, they are just mixing. Dissolving is not a chemical change.
63. Ethanol is a colorless liquid at −30°C
64. Neon is a colorless gas at 60°C
65. Sulfur is a solid at 7°C
66. As the temperature rises sulfur is natural solid will melt before mercury boils. Sulfur melts at 115 degrees C. and Mercury boils at 357 degrees C. However, all the substances on the chart will melt before Mercury boils, all melting under 357 degrees C.
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