Answer Key Review p. 19-20 1. You have a piece of metal that has a volume of 15 ml and a mass of 135 grams. What is the density of this metal? What is the identity of this metal? • 135 g / 15 mL = 9.0 g/mL • Copper! 2. What is the volume of a piece of gold which has a mass of 20 grams? (see table below for densities) • 20 g / 19.3 g/mL = 1.036g • 1 g with correct sig figs! 3. What is the mass of a piece of zinc which has a volume of 150 ml? • 7.1 g/mL x 150 mL = 1065 g • 1100 g with correct sig figs! 4. The density of mercury is 13.6 g/mL. If you have a sample of mercury with a mass of 306.0 grams, how many mL of mercury do you have? • 306.0 g / 13.6 g/mL = 22.5 mL 5. You have a statue that has a volume of 238 ml, and is made of pure silver. What does this statue weigh? • 10.5 g/mL x 238 mL = 2499 g • 2500 g with correct sig figs! (you would put a line over the bolded 0 or write the number in scientific notation to convey 3 digits in a case like this 2.50 x 103 g) 6. Archaeologists discover a crown which they believe to be gold. When they place the crown in a tub of water, the volume increases by 528 ml, and when they place the crown on a scale they discover it has a mass of 4,500 grams. Is the crown made of gold? Show your work and explain your answer. • 4500 g / 528 mL = 8.5 g/mL • This is about the density of brass, not gold! 7. What is the density of a substance which has a mass of 10 grams and a volume of 8 ml? • 10 g / 8 mL = 1.25 g/mL • 1 g/mL with correct sig figs! 8. You have a piece of metal which has a mass of 315 grams and a volume of 40 ml. What type of metal is this? • 315 g / 40 mL = 7.875 g/mL • 8 g/mL with correct sig figs! • Probably iron! 9. You have a piece of metal that occupies a volume of 30.0 mL and has a mass of 81.0 grams. What is its density? What type of metal is it?What is the volume of a metal which has a density of 2.7 g/ml and a mass of 15.0 grams? • 81.0 g / 30.0 mL = 2.70 g/mL • Aluminum! • 15.0 g / 2.7 g/mL = 5.555555 mL • 5.6 mL with correct sig figs 10. What is the mass of a metal which has a density of 19.3 g/ml and a volume of 30 ml? • 19.3 g/mL x 30 mL = 579 g • 600 g with correct sig figs! 11. If you have a piece of Zinc with a mass of 50 grams, what is its volume? • 50 g / 7.1 g/mL = 7.04 mL • 7 mL with correct sig figs! 12. A piece of copper wire and a 50-pound brick of copper both have the same density. In your own words explain how this can be true. • The mass divided by the volume will be the same. • If you have more mass, you will have to have more volume too. • But the ratio of mass to volume will be constant. 13. What is the definition of matter? • Matter is anything that has mass (weight) and takes up space (volume) 14. List TWO things that are NOT matter, and explain WHY they are not matter Examples include: wind, light, sound, democracy, fear, etc. They are not matter because either: they don’t weigh anything (no mass) Or they don’t take up any space (they are not physical objects) 15. List TWO things that ARE matter, and explain WHY they are matter • Answers could include anything that has mass and takes up space. • Examples: air, a table, Mr. C, etc. 16. Describe the purpose of the shower in the classroom- under what circumstances should it be used? • It is for rinsing off BIG chemical spills or possibly if you catch fire. • Neither of these situations is very likely, but if you feel you need to use the shower, DO IT! DON’T wait to ask permission first! But use your best judgement. Small spills can usually be rinsed off in the sink! 17. Describe when goggles should be worn in the laboratory. • Wear goggles whenever there are chemicals out. • Keep them on until Mr. C says to take them off! • Even chemicals at another lab station can splash or spill over toward you! 18. Describe what you should do if you break a piece of glassware in the lab. • Get the broom and dustpan to sweep it up. Then dispose of in the broken glass box. • Never use your hands! • Never put glass in the trash can! 19. Describe the function of the following pieces of equipment: • – Erlenmeyer flask - containing liquids (not measuring volume) – Funnel – preventing spills when pouring – Well plate – performing chemical reactions in a small space – Ring stand – holding equipment – Tongs – holding equipment (e.g. when too hot to touch) – Graduated cylinder – accurately measuring volmue 20. Identify the following pieces of equipment: • A. Beaker (for containing liquids, but NOT for measuring volume!) • B. Scoopula (for getting solid chemicals out of a bottle or container 20. Write the proper measurement • A. 73.0 mL • B. 27.5 mL (your answer may be slightly different. That’s ok. As long as it is 27.X – 20. C. If you measure exactly thirty milliliters of water using a pipette that has increments of 0.1 ml, how should you record this measurement? 30.00 mL – 20. D. If you weigh exactly twenty grams of a material on one of the balances in this room, how would you record the measurement? 20.00 g or 20.0 g depending on the balance
