CHM 1045 Summer 2007 Test 1: Chemistry Concepts and Calculations, Exams of Chemistry

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CHM 1045 Summer, 2007 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. A hypothesis is just an educated guess, but a theory has been proven to be true. What is wrong with this statement? What is the difference between a hypothesis and a theory?
2. Give one specific example of each of the following. a) a compound b) a solution that is not a liquid.
3. A physical process involves a change in a physical property. Give one specific example of a physical process and state the physical property that changes during the specified process. Your answer could be as short as two words.
4. What is the Law of Constant Composition (Law of Definite Proportions)? State it.
5. How does Dalton's Atomic Theory explain the Law of Conservation of Mass?
6. Give an example of two (specific) compounds to which the Law of Multiple Proportions applies.
7. If you heat 2.53g of metallic mercury in the presence of oxygen gas, the two will combine to form 2.73g of mercury oxide. What mass of mercury combines with 1.00g of oxygen?

8. How many significant figures are there in each measurement? a ) 0.0020mL b) 200.0s c) 127mi d) 1.20 x 10-3kg
9. Convert 10300.mg to kg
10. Convert 3.95 x 10-4cm to μm;m;
11. If carpet costs $15.00 per square yard, how many cm^2 can you buy for $1.25? (1yd=36in, 2.54cm=1in)
12. After his gold foil experiment, in which α particles were deflected at high angles, Rutherford proposed a new model of the atom. a) What modification of the model did Rutherford propose? What was new about his model of the atom? b) Why did Rutherford propose a new model for the atom?
13. An element has two naturally-occurring isotopes with the following masses and fractional abundances. Calculate the average atomic mass from this information. Isotope Isotope Mass (amu) Fractional Abundance (^63) X 62.930 0. (^65) X 64.928 0.

14. Fill in the 4 empty boxes in the following chart. Isotope symbol # protons # neutrons (^15) N 8 8 9 (^23) Na
15. What information or property does one measure using a mass spectrometer. "Mass" will not answer the question.
16. What is an anion? What are the formulas for the following compounds?
    17. sodium carbonate 18. calcium sulfide 19. iron(III) oxide What are the names of the following compounds?
    18. CuCl 2 21. BaSO 4 22. N 2 O 4
17. The formula for aluminum acetate is Al(C 2 H 3 O 2 ) 3. What is the formula for potassium acetate?
18. a) The formula unit for calcium fluoride is CaF 2. Specifically, what does this tell us? b) The molecular formula for ethanol is C 2 H 6 O. Specifically, what does this tell us? 5 points extra credit: Carbon and oxygen form two different compounds, A and B. The composition of samples of A and B were determined and are listed in the following table. Show that the data for these two compounds are consistent with the law of multiple proportions. Compound A Compound B Mass of sample analyzed 14.0g 5.5g Mass of carbon in sample 6.0g 1.5g Mass of oxygen in sample 8.0g 4.0g