June 2022  Chemistry Regents #36-40

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36 A student measured the melting point of a sample of gallium to be 309 K. Based on Table S, which numerical setup can be used to calculate the student's percent error?

(1) 309K-303K/303K  x 100

(2)  309K-303K/309K  x 100

(3) 303K/309K    x 100

(4)   309K/303K     x 100

 1   ignoring PEMDAS...ugg

Use Table S for the accepted melting point of Gallium

MP=309K

measured-accepted/accepted   x 100
37 Which chemical bond is most polar?

(1) a O-H bond in H2O

(2) a S-H bond in H2S

(3) a Se-H bond in H2Se

(4) a Te-H bond in H2Te

 1   largest difference in electronegativity

=most polar bond

electronegativities..Table J

H=2.2 O=3.4 S=2.6 Se=2.6 Te=2.1

subtract..largest difference wins
38 What is the amount of heat required to melt 43 grams of solid magnesium oxide at its melting point? The heat of fusion is 1.9 X 103 I/g.

(1) 2.3 X 10-2 J      (3) 8.2 X 104J

(2) 4.4 X  X 101 J  (4) 3.4 X 105 J

 3   q= m x Hf

q= 43g x 1.9 x 103 J/g= 81.7 x 103J

so 8.2 x 104 J

 

39 Given the diagram of a laboratory apparatus:

distillation summary | Britannica

This apparatus is used for which process?

(1) filtration

(2) distillation

(3) chromatography

(4) electrolysis

 2   eliminate the other 3 if you don't know it
40 Solid aluminum has a specific heat capacity of 0.90J/g.K. How many joules of heat are absorbed to raise the temperature of 24.0 grams of aluminum from 300. K to 350. K?

(1) 22J    (3) 1100J

(2) 45 J|  (4) 1200J

 3   q=mC delta T

q=24.0g x  0.90J/g.K x (350K-300K)

so 24 x 0.9 x 50= 1080==> 1100J

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-65 Questions 66-70 Questions 71-73 Questions 74-77 Questions 78-82 Questions 83-85

 

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