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Science ch.2 test
Science ch. 2
Question | Answer |
---|---|
What is a physical change and give examples? | A physical change alters the form(size, shape, or state) of a substance but doesn't change the identity of the substance. Ex: tearing paper, bending a nail. |
What is a chemical change and give examples? | A chemical change is when a substance changes into a new substance with different properties. Ex: burning anything, iron, rusting. |
What is thermal energy? | The energy of the movement of particles in a substance. |
What is chemical energy? | The energy that comes from the chemical bonds within matter. Stored in chemical bonds. |
When does matter change and what forms of energy are usually involved? | Matter changes (physically or chemically) whenever energy is added(absorbed) or taken away(released). Three different forms of energy that are usually involved are heat(thermal), light, or electrical. |
What is the Law of Conservation of Energy? | A scientific principle that states"during any physical or chemical change,amount of energy stays the same before and after the change."In other words,amount of energy that you had before the change equals the amount of energy you have after the change |
What is usually involved in a chemical change? | Larger amounts of energy are usually involved in a chemical change. |
What is a synonym for burning? | Combustion |
What is true about a substance's capability to change states? | Under certain conditions, a substance can change from any one state of matter to another. |
What are the five changes of state? | melting, freezing, vaporization, condensation, sublimation |
What is melting and give an example? | The change in state from a solid to a liquid. Ex: Water turning to ice. |
What is freezing and give an example? | The change of state from a liquid to a solid. Ex: Water turning to ice. |
What is vaporization? | Vaporization is the change of state from a liquid to a gas and occurs when a liquid gains enough energy to become a gas. |
What are the forms of vaporization? | Evaporation and boiling |
What is evaporation? | Vaporization only at the surface of the liquid. |
What is boiling? | Vaporization that occurs throughout the liquid as well as at the surface. |
What factor influences boiling point? What happens if you lower it? Increase it? | The boiling point of a liquid depends on the air pressure above the liquid.If you lower the air pressure above a liquid,you will lower the boiling point of the liquid.Raising the air pressure above the liquid causes the boiling point of a liquid to raise |
What city is an example of the air pressure and boiling point phenomenon and why? | Denver, Colorado has a lower air pressure because of its high altitude, so water boils at 95 degrees Celsius there. |
What is the condensation and give examples? | Condensation is the change of state from a gas to a liquid and occurs when a gas loses enough thermal energy for it to turn back into a liquid. |
What is sublimation and give examples? | Sublimation is the change of state from a solid directly to a gas and occurs when particles of a solid gain enough energy on the surface to become a gas. It does Not melt first. Ex: dry ice, moth balls, solid air fresheners |
What is absolute zero? | The temperature at which all molecular motion stops. That temperature is about -460 degrees F. (0 degrees Kelvin) |
What is a chemical reaction? | Another term for a chemical change. |
What do all chemical reactions do with energy? | They either absorb or release energy. |
How does energy from sunlight allow plants to undergo chemical reactions like photosynthesis? | It converts the sun's light energy into chemical energy. |
What does the sun converting light energy to chemical energy allow? | It allows plants to undergo chemical reactions like photosynthesis? |
What can chemical reactions release? | Heat, light, or electrical energy |
What do you affect by changing the temperature of the substances in a chemical reaction? | Rate of the chemical reaction |
What affects the rate of the chemical reaction? | Changing the temperature of the substances in a chemical reaction. |
What happens if you add heat energy? | You can speed up the rate of the reaction. |
How can you speed up the rate of the reaction? | By adding heat energy. |
What happens if you remove heat(chill)? | You can slow down the rate of the reaction. |
How can you slow down the rate of the reaction? | By removing heat(chill). |
What are the signs of chemical change? | The five signs of chemical change are color, property, temperature, production of gas, and production of precipitate. |
What is a precipitate? | To cause (a substance) to be deposited in solid form from a solution. |
What does the law of conservation of energy state? | The total amount of energy before and after a reaction states the same. |
What happens with energy in a chemical reaction? | Energy is either absorbed or released. |
What are examples of substances that sublimate? | Moth balls(napthalena)-salt, iodine, solid air fresheners, and dry ice |
What is deposition? | Changing from a gas to a solid in the proper conditions |
What is the opposite of sublimation? | deposition/desublimation |
What is a synonym for chemical change? | chemical reaction |
What is an inhibitor? | A substance that slows down the rate of a chemical reaction. |
What is a catalyst? | A substance that speeds up the rate of a chemical reaction. |
Are catalysts and inhibitors part of a chemical reaction? | No |
What is the formula for pressure? | Force/area |
Why is it important to monitor and adjust the air pressure in tires during long trips? Restate the question. | Tires get hot from the combination of the friction in the rubber tires and air outside. Temperature inside the tire increases.If temperature increases,then pressure increases as well according to Amonton's law.Pressure increasing could cause tire to burst |
Explain how ice is different than water keeping in mind movement and arrangement. Also remember that ice is a crystalline solid. Restate the question. | Particles of ice are tightly packed. Particles in solids vibrate in fixed positions. Ice is a crystalline solid so its particles are arranged in a regular, repeating pattern. Water particles are still packed fairly tightly but move freely. Particles touch |