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Chemistry DUT 2
Chem Test 2
Question | Answer |
---|---|
Physical properties | can be observed and measured without changing the kind of matter being studied. |
Melting point | The temperature at which a solid can change to a liquid; this temperature remains unchanging under constant conditions. |
Ice melts at _____ degrees Celsius and ______ degrees Fahrenheit. | 0 degrees C, 32 degrees F |
Boiling point | the temperature at which liquids boil and change states from a liquid to a gas. |
The boiling point for pure water at sea level is _____ degrees Celsius or ______ degrees Fahrenheit. | 100 degrees C, 212 degrees F |
Density | a property that describes the relationship between the mass of a material and its volume. |
Substances that are denser contain more ________ in a given volume. | matter |
Density is a size _____ physical property, meaning that it does not change no matter how large or small the sample. | independent |
Physical properties used to help identify a substance | melting point, boiling point, density, and color or absence of color |
Chemical properties | can be recognized only when substances react or do not react chemically with one another, that is, when they undergo a change in composition. |
Examples of chemical properties | ability to rust and ability to burn |
Ability to burn | a chemical property that involves a substance reacting quickly with oxygen to produce light and heat. |
Ability to rust | a chemical property that involves a substance reacting slowly with oxygen. |
Physical changes | do not change the composition of a substance, only the physical properties. |
When a substance changes from one state of matter to another, the ___________ of the substance remains the same. | composition |
Examples of change in state | melting of ice cream, hardening of melted wax, or evaporating of water from wet clothes. |
Sublimation | When a substance changes directly from a solid to a gas |
Deposition | When a substance changes directly from a gas to a solid |
Dry ice and solid air fresheners are examples of ____________. | sublimation |
Water vapor forming frost is an example of ___________. | deposition |
Examples of physical changes | change in state of matter and change in size or shape. |
Cutting, tearing, dissolving, stretching, or wrinkling are all examples of _______. | change in size or shape |
Chemical changes | result in the formation of one or more new substances with new chemical and physical properties. |
Evidence of chemical changes | color change, temperature change, formation of a precipitate, formation of a gas |
Precipitate | when two solutions are combined and form a solid |
Substances can be classified as acids, bases or neutral based on their ____ | pH |
Acids and bases are solutions usually with ______ as the solvent. | water |
pH scale | a way to measure how acidic or basic a solution is. |
The pH range of a solution | between 0 and 14. |
The pH of pure water is ___ | 7 |
Any solution with a pH of 7 is a _______ solution. | neutral |
The pH of an acidic solution is ____ than 7 | less |
The lower the pH, the more _______ the solution. | acidic |
The pH of a basic solution is _______ than 7 | greater |
The higher the pH, the more _______ the solution. | basic |
_____ can be identified by their sour taste and by their reaction with some metals. | acids |
_____ can be identified by their bitter taste and their slippery feel. | bases |
Acids and bases ___________ each other. | neutralize |
Indicators | substances that can be used to determine whether a solution is acidic, basic, or neutral. |
Litmus paper | Has a special dye on it that changes colors in the presence of an acid or base. |
Blue litmus paper turns red in an ______, and stays blue in a _____. | acid, base |
Red litmus paper turns blue in a _______, and stays red in an _______. | base, acid |
Both red and blue litmus paper turn ______ in a solution that is neutral. | violet |
Phenolphthalein | is used to test for the presence of a base |
Phenolphthalein is a colorless chemical that turns magenta in a ________, and stays colorless in an ______ or _______ solution. | base, acidic, neutral |
pH paper | Has a range of colors depending on the pH of the solution; the color of the paper is compared to the chart on the vial to determine the pH. |