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Acid and Bases - Alien II
Contributed by: The RAND Institute (RAND)

Alien Recipe Version

Part 1 (Page 2)
1a 1 pt Orange, Golden-orange
1b 1 pt 5
1c 1 pt Acid

Part 2 (Page 3)
2a 1 pt note: Blue, Dark blue, Blue-green are not acceptable. Green, Dark green
2b 1 pt 9
2c 1 pt B (too basic)

Part 3 (Page 5)
Table 1 9 pts
Score 1 pt for each correct pH number. If the number is wrong, mark the answer incorrect, even if the student has listed the correct color. However, if the number is missing, award points for correct color.
Answer Row 1 10-11 Blue, Purple

Row 2 6-8 Greenish Yellow, Yellow

Row 3 1-3 Pink, Rust Brown, Red

Row 4 9-11 Dark Green, Green, Blue

Row 5 11 Blue, Purple

Row 6 9 Green

Row 7 9 Green

Row 8 6-8 Greenish Yellow, Yellow, Light Green

Row 9 4-6 Yellow Orange, Orange, Golden Orange
(Row 9 must have a lower pH number or more acidic color than row 8.)

PART 4: (Page 6)

4a 1 pt- Medicine C

Note: 4a is a gateway point for 4b. Award no points for 4b if 4a is incorrect.

4b 1 pt- C brings the blood back to normal or neutral or pH of 7 or to yellow or "evens out," "balances," or "stabilizes" the blood.

1 pt- Mentions 1 or more of the following:

  1. C is acidic and the blood is too basic.
  2. C lowers the pH of the blood (to yellow or neutral).
  3. Medicine A made the blood more basic and B had no effect.

Note: "It" rule: If the student uses the pronoun "it" the reference must clearly be to the solution of medicine and blood, not just to the medicine. If this is not clear, award no points.

Note: Award no points for 4b if the student states that medicine C itself is closer to neutral; the correct answer is that C can neutralize the blood.

4c 1 pt- By adding any one of the following or any combination of them (a combination can include Medicine B as well):
  1. an acid or solution with a low pH
  2. Solution X
  3. Medicine C
4d 1 pt- By adding either of the following or a combination of them (a combination can include Medicine B as well):
  1. a base or solution with a high pH.
  2. Medicine A

Part 5 (Page 7)
5a 1 pt - Fish stopped dying because Pro-Base made the pond less acidic, returned the pH to neutral, or balanced the water.

1 pt- Fish began dying again because additional Pro-Base made the pond water too basic, or the pH went past neutral to make the pond basic.

Note: Answers which make no reference to "base" or "neutral" or pH - e.g., "They gave it too much," or "They need to give it less," or "It was too strong," or "They gave it the right amount" - are not acceptable.

5b 1 pt - B (Add an acidic substance)
5c 1 pt - The acid is needed to bring the water from a base back to neutral pH, e.g. "It brings it back to neutral," "To reverse the process," or "Balance the water," is also an acceptable answer.

1 pt - But stop adding acid when the water has become neutral. The response must provide enough information to tell how to proceed correctly, e.g., what amount is needed to get to neutral, or what actions would disrupt neutrality.


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