Name: _________________________
Lab Sec. Number: ___________
There is a periodic table at the end of this exam. On multiple choice questions, circle the “best” response for each question. On questions that require calculations, show all pertinent work to receive partial or complete credit.
1. (5 points) A 25.49 g sample of iron is place in a graduated cylinder that is about half full of water. If the water level before adding the iron was 10.25 mL and the density of iron is 7.87 g/cm3, what will be the water level after adding the iron?
a.
13.49
b. 186.77
c. 11.82
d. 13.10
2. (5 points) When reading a graduated scale your eyes should be________________ the scale.
a.
level
with
b. below
c. above
d. underneath
3. (5 points) Water in a narrow glass tube has a curved surface known as the ________________.
a. concavity
b. resonance line
c. hyperclave
d.
meniscus
4. (5 points) A liquid has a density of 2.227 g/mL. How many milliliters do I need to measure in order to have 77.92 g of the liquid?
a.
13.86 b.
34.99
c. 0.03465 d. 34.65
5. (5 points) What is the percent by weight phosphorous in NaH2PO4?
25.8%
6. (5 points) (Not applicable) A thermistor can be used to measure temperature because _______________.
a. it contains a resistor through which the current flow changes as a function of temperature
b. it contains mercury that flows to different levels with temperature
c. it has a digital readout that gives the temperature
d. it changes shape as a function of temperature
7. (5 points) When calibrating a thermistor you should ___________.
a. always use a dead fish for a reference temperature
b. only perform one point calibrations, they are more accurate
c. always do a two point calibration
d. Use two or more
calibration temperatures close to the expected measuring range
8. (5 points) If you hold a beaker in your hand that contains an exothermic reaction the beaker will _______________.
a. become colder
b. become warmer
c. not change in temperature
d. fluctuate up and down in temperature
9. (5 points) When working in a spreadsheet, such as Excel, multiple calculations on a set of data can be performed by _________________.
a.
doing the
calculation once then copy it for each of the other data points
b. doing the calculation over and over again
c. telekinetically willing the computer to complete the operation
d. clicking on the multiple performance enhanced mode
10. (5 points) (Not applicable) In an experiment to determine the simplest formula for a silver oxide, the following data was collected:
wt crucible + cover 13.1441 g
wt. crucible + cover + Ag 13.4628 g
wt. crucible + cover + oxide 13.4864 g
Determine the empirical formula for this silver oxide
Ag2O
11. (5 points The following reaction is a _____________________.
Ba(OH)2 (s) ---------> BaO (s) + H2O (g)
a. single displacement b. direct synthesis
c. decomposition d. double displacement
12. (5 points) The formula for nitric acid is _______________________-.
a. NaOH b. HNO3 c. HCl d. *#$*%@*&@!!
13. (5 points) You recovered 45.66 grams of copper in a experiment that had 73.4% yield. What was the initial mass of copper reacted?
a.
62.2
b. 1.61
c. 33.5
d. 3.35x104
14. (5 points) Sulfuric acid was used to dissolve the copper II oxide in experiment 4, write the balanced reaction for these two compounds. (Indicate the correct phases for the products and reactants.)
H2SO4(aq)
+ CuO(s)
® CuSO4(aq) + H2O(l)
15. (5 points) List the proper number of significant figures for each of the following:
a. 8.701x10-3 __4__
b. 0.00901 __3___
c. 7200. __4__
d. 401.6 __4___
e. 3.004x10+5 __4__
16. (5 pts) You add 299.0 g of water at 47.5 °C to 225.0 g of water at 14.3 °C. The final temperature of the water when the system reaches thermal equilibrium is 30.6 °C. What is the heat capacity of the container holding the cold water? [Heat capacity of water is 1 cal/(g· °C)]
Ccal = 85.0 cal/°C
17. (5 points) An acid-base reaction produces heat. This is known as a(n) ________.
a. exothermic process b. systematic process
c. extended process d. endothermic process
18. (5 points) Based on the following balanced equation, calculate the number of grams of iodine (I2, FW= 253.8 ) that would be produced when 26.144 grams of potassium chlorate (KClO3, FW=122.55) reacts with excess potassium iodide (KI). [assume a complete reaction].
ClO3—(aq) + 6 I— + 6 H+(aq) ® 3 I2(aq) + 3 H2O(l) + Cl-(aq)
162.4 g I2
19. (5 points) In the following reaction:
6 Fe2+(aq) + K2Cr2O7(aq) + 14 H+(aq) ® 6 Fe3+ (aq) + 2 Cr3+(aq) + 7 H2O(l) + 2 K+(aq)
The species oxidized is ________________ and the species reduced is ______________. (circle the correct response that completes the blanks in the proper order.)
a. chromium in K2Cr2O7; Fe2+
b. H+; Fe2+
c.
Fe2+;
chromium in K2Cr2O7
d. potassium in K2Cr2O7; H+
20. (5 points) ______________________ Pseudonym for posting your lab grades. Minimum of 6 letters and/or
numbers, maximum of 15. (If you
already gave one to your
Extra Credit (5 points)
Manganese