Hello class,
Just posting my questions, going to work on them later.
Ch. 7 Question 49
Silver is often extracted from ores such as K[Ag(CN)2] and then recovered by the reaction
2K[Ag(CN)2] (aq) Zn(s) ⟶ 2Ag(s) Zn(CN)2(aq) 2KCN(aq)
(a) How many molecules of Zn(CN)2 are produced by the reaction of 35.27 g of K[Ag(CN)2]?
First, I need to make sure that my equation is balanced and thankfully it is already balanced because balancing is kind of frustrating.
Next, the first question is asking for the molecules of Zn(CN)2 (Zinc Cyanide).
Molar mass of K[Ag(CN)2] is 199g (which I calculated from the periodic table).
I have 1 mol of Zn(CN)2 and 2 mol of the ore K[Ag(CN)2] so the ratio will be 1:2.
Also, since I need to find moles, I will use Avogadro’s number here.
I plugged in everything in stoichiometric factor:
35.27 K[Ag(CN)2x1mol199g K[Ag(CN)2x1mol Zn(CN)22mol K[Ag(CN)2×6.022x10231mol
The answer I got was 0.5337 but I need to move my decimal over since my number needs to begin with a 1-9 so it’ll be 5.337 and since I moved the decimal to the right one time I take away one from 1023 to become 1022
= 5.337×1022 Molecules of Zn(CN)2
(b) What mass of Zn(CN)2 is produced?
I calculated the mol of Zn(CN)2 (by calculating the equation without Avogadro’s number)
35.27g K[Ag(Cn)2 x1mol199g K[Ag(CN)2x1mol Zn(CN)22mol K[Ag(CN)2=0.0886mol Zn(CN)2
I used the periodic table to calculate the molar mass of Zinc Cyanide = 117.42g.
I multiply the mol by the molar mass: 0.0886 x 117.42g to get
= 10.40g production of Zn(CN)2
Ch. 9 Question 53
Homes may be heated by pumping hot water through radiators. What mass of water will provide the same amount of heat when cooled from 95.0 to 35.0 °C, as the heat provided when 100 g of steam is cooled from 110 °C to 100 °C.
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