CHM 1045 Spring 2008 Test 1: Chemistry Concepts and Calculations, Exams of Chemistry

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CHM 1045 Spring 2008 Test 1 Name (print)___________________ Show your work for complete (and partial) credit. Report your answers to the correct number of significant figures, and use units where appropriate.

1. What is the most important difference between a hypothesis and a theory?
2. A physical change/process involves a change in a physical property. Please demonstrate this: cite a particular physical change, then indicate what physical property changes, and note what this physical property changes from and to. Physical Change Physical property Changes from: To:
3. The value 0.0500213g is expressed to a precision of: (check all that apply) ___ 10-7g ___ .001mg ___ .1μgg ___ .0001mg ___ .01μgg
4. Convert 2.000mg to g
5. Convert 4.57 kg to mg
6. Convert 2.71 x 10^5 cm^2 to m^2.
7. The liquid compound octane has a density of 0.702g/cm^3. What is the volume of 12.0g of octane?

8. If sheet metal costs $9.00 per square foot, how much would one square centimeter cost? (2.54cm=1in)
9. The Law of Definite Proportions (Law of Constant Composition) applies to: (check all that apply) ____ solutions. ____ ionic compounds. ____ homogeneous mixtures. ____ molecular compounds. ____ all mixtures.
10. How does Dalton's Atomic Theory explain the Law of Definite Proportions?
11. Show that the law of multiple proportions applies to the following information concerning two compounds composed entirely of sulfur and oxygen. Compound Mass of compound Mass of sulfur Mass of oxygen Compound A 1.00g .500g .500g Compound B 1.00g .400g .600g
12. a) What subatomic particles are responsible for almost all the mass of an atom? b) In an uncharged atom, the number of electrons is equal to the number of ________________.

13. An element has two naturally occurring isotopes with the following masses and abundances. What is the atomic weight of the element? Isotope mass (amu) % Abundance 84.9118 72. 86.9092 27.
14. How is the formula unit for an ionic compound similar to an empirical formula for a molecular compound?
15. What is the name of each compound? a) LiCl b) K 2 O
16. a) N 2 O 4 b) Cu 2 CO 3
17. What is the formula for each compound? a) iron(II)sulfate b) ammonium sulfide
18. a) calcium nitrite b) magnesium fluoride
19. The formula of calcium hydrogen phosphate is CaHPO 4. What is the formula for lithium hydrogen phosphate?
20. Balance the following equation. ____Na 2 S 2 O 3 + ____I 2 → ____NaI + ____Na 2 S 4 O 6