CHEMCOM
TEST 1.C
Matching(1-5)
1) The quantity or mass of solute which is dissolved in a given mass of solvent(usually in 100g of solvent or in ppm or as a percentage)
2) The substance which dissolves
3) Describes a solution in which no more solute could dissolve.
4) Describes the normal maximum concentration for a solute in a solvent(expressed as "____grams of solute/100grams of water") This property depends on temperature.
5) Capable of dissolving
a) concentration b) solute c) soluble
d) solubility e) unsaturated
6) Water can dissolve ionic compounds. Which idea best describes how this happens
a) ionic compounds fit in between water molecules
b) charges on water molecules attract the ions in compounds with the
opposite charge
c) nonpolar bonds are made between water and ionic compounds
d) water has no charges while ionic compounds have charges
7) For gases dissolving in liquids , an increase in temperature______
a) does not change solubility b) increases solubility c) decreases solubility d) makes solutions less concentrated
8) For solids dissolving in liquids , an increase in temperature______
a) does not change solubility b) increases solubility c) decreases solubility d) makes solutions less concentrated
9) What is the greatest amount of KCl that may be dissolved in 100g of water at 50oC?
a) 33 g b) 43 g c) 50 g d) 72g e) 82 g
10) What temperature is needed to dissolve 130 g of KNO3 in 100 grams of water.
a) 21oC b) 27oC c) 69oC d) 78oC e) 100oC
11) Which substance has the lowest solubility at 0 oC ?
a) KNO3 b) KCl c) NaCl d) all are the same
12) Water is saturated at 28 oC with oxygen. The temperature of the water is cooled to 4 oC. How much oxygen must be added to 1000g of water to keep it saturated?
a) 1 mg b) 3 mg c) 4 mg d) 5 mg e) 6 mg
13) Which of these would most greatly increase aeration ?
a) decreasing the amount of sewage b) lowering the pH of the water
c) removing heavy metals from the water d) placing a dam in a stream
e) raising the water level of a stream
14) Commonwealth Edison removes water from the DesPlaines River in Joliet to use in its electric power plant. The water leaving the power plant would
a) be cooler and have a lowered oxygen concentration
b) be warmer and have a lowered oxygen concentration
c) be cooler and have a higher oxygen concentration
d) be warmer and have a higher oxygen concentration
15) Photosynthesis effects the amount of dissolved oxygen in water. Which statement is true
a) it increases D.O. during the day b) it decreases D.O. during the day
b) it increases D.O. during the night and day d) it decreases the D.O. during the night and day
16) Heavy metal ions damage ______molecules in the humans ______systems
a) protein...... respiratory, digestive and reproductive
b) carbohydrates ...... reproductive, nervous, and muscle
c) protein...... kidney, liver and nervous
d) DNA ...... reproductive liver and kidney
17) Two eagles have been exposed to poison set in bait to kill coyotes on cattle ranches. Which of the factors below will not be important in understanding how the 2 eagles will be effected?
a) the type of poison b) the total dose each received
c) the frequency each was exposed d) whether the poison is natural or man made e) the weight of the eagles
18) A pond is contaminated with a chemical that is a base. Which ion should be present in large amounts
a) H+ b) OH- c) Cd+2 d) SO4-2 e) Ba+2
19) On the pH scale Lake Andrew has a pH of 5.9 and Lake Michigan has a pH of 8.2 From this information you could conclude......
a) they are both polluted b) Lake Andrew has acid in it
c) Lake Michigan has acid in it d) Both lakes have acid
e) both lakes have a base in it
20) Acute toxicity refers to ______of a poison
a) the dose b) the short term effects c) the route of exposure
d) the time it takes for a poison to act e) all of these
21) The amount of a substance which first shows a toxic effect is the
a) threshold limit b) dose c) acute amount d) chronic amount
22) The process by which sewage and organic waste is consumed by aerobic bacteria is
a) biodegradation which lowers D.O levels in streams
b) biodegradation which raises D.O levels in a stream
c) photosynthesis which lowers D.O levels in streams
d) aeration which raises D.O levels in streams
e) respiration which raises D.O levels in streams
23) A person's home has lead joints in its copper water pipes. In which case is the person likely to get the most lead ion in the drinking water
a) cold acidic water is sent thru the pipes
b) cold basic water is sent thru the pipes
c) hot acidic water is sent thru the pipes
d) hot basic water is sent thru the pipes
e) all examples will be the same
24) Acetic acid has polar covalent bonds. Water is polar covalent bonds. Acetic acid will dissolve in water.
a) true b) false
25) Which of these dissolve in a polar solvent
a) an ionic compound b) a polar compound c) a nonpolar compound
d) a and b e) a,b,and c
Essay 1.C
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DO ANY 5 of 6 QUESTIONS
** Answer in complete sentences. **
In calculations show how problems are set up. Math may be done on calculators
All number answers must have units for full credit
1a) A student makes a solution for lab. The solution contains 0.8 grams of lead ion and 99.2 g of water Find the concentration in pph
1b) Find the concentration in ppm of a solution that has .005 grams of lead ion in 12,500 grmas of water
1c) the EPA threshold limit for lead in water for humans is .010 ppm; use the answer to part b and find the risk factor for lead
1d) Is the solution dangerous to drink______
2) Write these formulas
a) Sodium phosphate______b) Copper (II) sulfide______
c) Sodium oxide ______c) trinitrogen diphosphide______e) lead (II) cyanide______
3) The residents of Lake Edward have noticed that a foul odor occasional comes off the lake. Members of the Lake Commission have D.O. readings taken every 6 hours in the middle of the lake. The readings are plotted below.All levels are well below 100% saturation. Use the map and the data to come up with at least 2 hypotheses about why the D.O. levels occasionally fall. Explain each hypothesis thoroughly.
Hypothesis I ______
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HypothesesII______
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4) A local newspaper ran this article about pollution of the Little Calumet River.
"Scientist from the EPA have monitored heavy metal contamination for the last 5 years in the Little Calumet. The EPA has found 4 heavy metals present in the water. Lead is present at .0023 ppm; copper is present at .01 ppm; iron is present at .0045 ppm and cadmium is present at .0007 ppm. Riverdale Mayor George Matke said, "We are presently concerned about the threat from copper pollution in the river. The other metals are present in much lower concentrations and do not appear to threaten fish in the river"
Take a position in which you agree or disagree with the mayor. Explain your position
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5) A fish kill has occurred on a lake in your town. No one knows the cause.
You are the expert. List and explain 3 different possible causes for the fish kill that you would have scientist investigate(clue be specific: at this point you should not just say "pollution" try to apply what you learned in this section about possible causes) YOU WILL BE GRADED ON HOW SPECIFIC YOUR ANSWERS ARE AND HOW DIFFERENT THEYA ARE FROM EACH OTHER
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6) Below are 3 pictures of a substance being put into water. Answer 3 questions for each picture.
a) Is the substances that is in the center an ionic nonpolar or polar substance B) will it dissolve in water C) explain why it will dissolve or why it will not dissolve
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- B)______
- C) ______
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