Chemistry+Ch1

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= KEY CONCEPTS – Print out the Chapter 1 Review Sheet from my website. Answer the questions, then compare your answers to the answers below: = = = = = =1. Calculate density given mass and volume.= Example. – A 5 g block has dimensions of 5 cmX2 cm X3 cm. What is the density? V = LxWxH (5 cmX2 cm X3 cm = 30cm3) D = M/V ( D=5g/30cm3 = 0.166 g/cm3)

** 2. Find the mass given the density and volume. ** Aluminum has a density of 2.7 g/cc. What is the mass of a 10 cc piece of Aluminum? D=M/V 2.7 g/cc = M/10cc M= 27 g

** 3. Know why density can be used to help identify materials. ** Denisty is a characteristic property. It NEVER changes.

** 4. Determine whether objects can sink of float based on comparing densities. ** EXAMPLES: Water has a density of 1 g/mL. Objects with density greater than 1 g/ml will sink in water, less than 1 g/mL will float. Rubbing alcohol has a density of 0.8 g/mL. Objects with density greater than 0.8g/ml will sink in rubbing alcohol, less than 0.8 g/mL will float.

** 5. Determine how liquids will layer in a container based on densities. ** ** 6. Give example of characteristic properties. ** EXAMPLES: Density, Boiling point, Freezing point, Melting Point, Chemical Acticity For pure water: Density: 1 g/mL Boiling Point: 100 °C Freezing Point: 0°C Melting Point: 0°C

7**.Recognize examples of heterogeneous and homogeneous mixtures**.

**8. Tell whether something is a mixture or a pure substance. Explain how you can tell whether something is a mixture or pure substance**.

**9. Know that elements and compounds are both pure substances and understand why**.

10. label a diagram of a molecule, recognizing that atoms make it up.

**11. tell whether something is a physical change or a chemical change**.

Practice questions: **1. Describe how you’d find the volume of an irregular shaped object**.

**2. A toy car has a mass of 25 grams. You fill a graduated cylinder with 50 mL of water. When you place the car in, the water level rises to 76.2 mL. What is the density of the car? Will it float or sink in water**?

**You find the density of a salt water mixture to be 1.2 g/mL. Will the car float or sink in the salt water**?

** 4.Label the following as physical or chemical changes: ** Chem -Rusting nail Chem-baking a cake Chem -Burning paper Phys-making chocolate milk Phys -Cutting hair Phys -making lemonade Phys -Painting Phys- separating the colors in ink with chromatography Phys-Boiling water Phys-using a filter to take coffee grinds out of your coffee

** 5. Identify the following as heterogeneous or homogeneous mixtures: ** Heterogeneous- Chex mix Homogeneous- pulp free orange juice Heterogeneous- Italian salad dressing Homogeneous- sugar water Homogeneous- Salt water Homogeneous- milk

** 6. Identify the following as mixtures or pure substance: ** Pure- Iron Pure- water Pure- carbon dioxide Mix-Coke Mix- sugar water Pure- oxygen Pure- Sugar Pure- alcohol Mix- salt water