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68 Determine the oxidation state of carbon in the salt used to produce a bright-red color. [1]
69 Explain, in terms of subatomic particles and energy states, how the colors in a fireworks display are produced. [1]
Sample Regents Questions
Base your answers to questions 70 and 71 on the information below.
A scientist makes a solution that contains 44.0 grams of hydrogen chloride gas, HCl(g), in 200. grams of water, H2O(l), at 20.°C. This process is represented by the balanced equation below.
HCl(g) H2O H+(aq) + Cl (aq)
70 Based on Reference Table G, identify, in terms of saturation, the type of solution made by the scientist. [1]
71 Explain, in terms of the distribution of particles, why the solution is a homogeneous mixture. [1]
Jan 2012 #70
Answer
P.S./Chem.–Jan. ’12
Answer: Unsaturated solution
Explanation:
1. The question is asking about 44 grams of HCl in 200 grams of water. We need to convert these
values to 100 grams of water so that we can use Reffy, Table G (p. 3). Let’s divide both the grams of water and the grams of solute by two:
200/2 = 100 grams of water
44/2 = 22 grams of solute
2. Now, let’s find the intersection between 20°C (bottom of table) and 44 grams (left side of table).
3. Does this point fall on, under, or above the HCl line?
This point falls under the HCl line and the solution is therefore unsaturated.
[11] [OVER]
UNIT 7: SOLUTIONS / SOLUBILITY © 272
