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Density
Chemical and Physical Changes
Elements, Compound, and Mixtures
Homogeneous or Heterogeneous?
Random
100
List the different units used to measure the volume, mass, and density
Volume =centimeters cubed (cm3) and =milliliters (mL) Mass: grams (g) or kilograms (kg) Density = grams per centimeter cubed (g/cm3) and grams per milliliters (g/mL).
100
1.Explain the difference between chemical and physical changes.
Chemical changes are changes in which two substances combine to create a new substance with different properties. They cannot always be reversed but sometimes they can be reversed with another chemical change. Physical changes occur when two substances are combined and each retains the same properties as the elements that make it up.
100
21. Define each of the following terms: element, compound, and mixture.
Element: a pure substance that is composed of only one type of atom. It cannot be broken down into simpler substances. Compound: a pure substance that is composed of two or more elements that are chemically combined. They combine to make a new substance with different properties. Compounds can only be separated by chemical reactions. Mixture: a substance that is composed of two or more elements that are physically combined. Each element keeps its own identity and properties. Mixtures can be physically separated.
100
sand and water
heterogeneous
100
16. What happens when you place an object with a density of 2.5g/cm3 into water that has a density of 1.0g/mL? Explain why your answer would happen.
The object would sink because it has a higher density than the water.
200
What is the weight of the ethyl alcohol that fills a 200mL container? The density of ethyl alcohol is 0.789 g/mL.
157.8 grams
200
7. List four different evidences of a chemical change.
Change in color, odor, the release of energy or heat, light, sounds, and bubbling or fizzing.
200
24. Compounds can only be broken down by a chemical change. List two specific ways to break down compounds.
adding heat or electrolysis (separating by electrical shock) Many answers accpeted
200
ocean water
homogeneous
200
how many phases does a homogeneous mixture have?
1
300
Explain what happens when you put liquids (that don’t mix) of different densities into a graduated cylinder?
The liquids with the highest densities would sink to the bottom to form layers. The layer on the top would be the liquid with the lowest density.
300
3. List four physical properties of matter. 4. List four chemical properties of matter.
physical properties of matter: color, shape, size, state, melting point, freezing point, boiling point, malleability (the ability to bend), density, volume, mass, or solubility (the ability to dissolve) chemical properties of matter: flammability (the ability to burn), reactivity with oxygen or water, or reactivity with acid (including vinegar).
300
26. Elements join to form compounds in a specific ______________.
mass ratio, known quantity, many answers accepted
300
stainless steel
homogeneous
300
22. Write a chemical formula that represents a compound and one that represents an element.
Element: only one capital letter! C, H, Cl, Mg4, F8. Compound: two or more capital letters! C6H12O6, H2O, CO2, H2O2.
400
10. How would you find the volume of a solid? 11. How would you find the volume of a liquid?
10. Measure the sides and multiply length x width x height. 11. Use a graduated cylinder
400
5. Changes of state are considered which type of change(physical or chemical)? Explain why.
Changes of state are physical changes because the substance still has the same chemical properties, just in a different form. Water is still water (H2O) when it is a liquid, solid (ice), or gas (water vapor).
400
27. How is a compound different from a mixture?
Mixtures DO NOT combine in a specific ratio, they are physically combined and can be separated, the elements in the mixture keep their physical properties, and they do not form a new substance.
400
salad
heterogeneous
400
17. Jack has a rock. The rock has a mass of 6g and a volume of 3cm3. What is the density of the rock?
D = m/v so the density of the rock equals 6/3. Density = 2 g/cm3.
500
14. How can you find the density of an unknown liquid?
1) find graduated cylinder 2)pour some of the unknown liquid into the graduated cylinder, and note the volume. 3) find the mass of the Liquid after subtracting out graduated cylinder mass. 4) divide the mass of the liquid by the volume of the liquid to calculate the density.
500
2.Why are chemical properties harder to observe than physical properties?
Chemical properties change the substances identity or makeup. They must involve a chemical reaction.
500
25. Why are compounds considered to be a pure substance?
It is a pure substance because compounds are composed of only one type of particle and the particles are chemically combined.
500
carbon dioxide
trick question! compound!
500
19. Alicia has a watch. It has a mass of 4g and a density of 0.8g/cm3. What is the volume of the watch?
D = m/v so the volume of the watch is 0.8 = 4/v. What goes into 4, 0.8 times? Volume = 5 cm3.