OOO AT&T; LTE T 13%, 8:50 PM toro csudh.edu 0.5 points Save Answer Question 19 I

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OOO AT&T; LTE T 13%, 8:50 PM toro csudh.edu 0.5 points Save Answer Question 19 In going from the top to the bottom of the activity series below, the which means that ease of oxidation of the metal An Activity Series for Metals in Aqueous Solution Metal Oxidation Reaction Lith K (ag) Ca (ag) 2 Alu Zn (ag) 2 a. increases. zinc ions can oxidize magnesium. b. decreases, magnesium can reduce zinc ions. C. increases, magnesium can reduce zinc ions. d. increases, magnesium ions can oxidize zinc e. decreases, zinc can reduce magnesium ions. 0.5 points Save Answer Question 20 According to the first law of thermodynamics, which of the changes, A-D, will always increase the internal energy of a system? (q energy transferred, and w work done) q 0, w 0 q 0, w 0 O d, g 0, w 0 e. None of the changes A-D will always increase the internal energy of a system 0.5 points Save Answer Question 21 How much work does a gas do when it expands against a constant pressure of 0.500 atm from a volume of 50.00 mL to a volume of 350.00 m L? (101.3 J 1 L atm) a. 15.2 J b. 5.2 J O C. 0.150 J d -0.152 J 0.5 points Save Answer Question 22 Ammonium nitrate sometimes is used in cold packs because its enthalpy of solvation in water is +21 kJ/mol. What is the minimum amount of ammonium nitrate (80.05 g/mol) that is needed to cool a or l) and ite

Explanation / Answer

H in electrochemical series is set to zero.

Below which reduction potential increase and reduction becomes more easy.

Above H there reduction potential decrease and easy of oxidation increases. Oxidation is the removal of electrons. So the species that has more capacity to loose electrons is good reducing agent.

Q. 19

By using above criterion we can answer this question by choosing option b.

Since as we go down in this series oxidation ability is decreased. Magnesium is above to Zinc so it must have more ability to oxidize than Zn and so it reduces Zn.

Ans: b decreases , magnesium can reduce zinc ions.

Q. 20

Lets write first law of thermodynamic in mathematical form.

Internal energy (Delta E) = q + w

From this equation we can say that when only we have both q and W are greater than 0 , there is always increases in internal energy.

In other cases, it is not necessary to increase it.

So the answer is option b.

b. q>0 w>0

Q. 21

Here we use following formula.

W =- p Delta V

Here p is pressure in atm , Delta V is change in Volume. (Final volume – initial volume)

Conversion of volume in L

Initial volume Vi = 50.00 mL x 1 L / 1000 mL = 0.050 L

Final volume Vf = 350.00 mL x 1 L / 1000 mL = 0.350 L

Lets plug given values

W = - ( 0.50 atm ) x ( 0.350 – 0.050 ) L

= - 0.15 L atm

Now we have to convert L atm to J

1 L atm = 101.325 J

Lets use this conversion factor to calculate work done in J

Work done in J = - 0.15 L atm x 101.325 J / 1 L atm

= -15.20

=- 15.2 J

So the answer for this question is option b : -15.2 J

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