1. barium nitrate reacts with magnesium sulfate 2, calcium reacts with water 3.
ID: 867378 • Letter: 1
Question
1. barium nitrate reacts with magnesium sulfate 2, calcium reacts with water 3. ammonium nitrate reacts with sodium carbonate 4. Heptane (C7H16) bums in air Do the following two questions on the REVERSE side of this page and loose-leaf, if necessary. 5. The Ka of H2PO4^-1 is 6.17 x 10^-8. Determine the pH of a 6.2 x 10^-4 M solution. 6. Given the following chemical reaction for the combustion of decane: a. Balance this reaction. b. 6.1 g. of sulfuric acid reacts with 7.1 g of copper. Determine: 1. the limiting reactant. 2. the volume of the sulk dioxide produced..Explanation / Answer
1) Ba(NO3)2 + MgSO4 -----------------> BaSO4 + Mg(NO3)2
white ppt. of barium sulphate magnesium nitrate
2) Ca + 2H2O --------------------> Ca(OH)2 + H2
slaked lime hydrogen
3) 2NH4NO3 + Na2CO3 ----------------------> 2NH3 + CO2 + 2NaNO3 + H2O
4) C7H16 + 11O2 ---------------------> 7CO2 + 8H2O
5) H2PO4- will furnish H+ as per the equilibrium
H2PO4- <===> H+ + HPO42-
Therefore Ka = [H+][HPO42-]/[H2PO4-] = X2 /6.2 x 10-4 { as X << 6.2 x 10-4 }
so X = (6.17 x 10-8 x 6.2 x 10-4)1/2 = 6.18 x 10-6 M = [H+]
hence pH = - log [H+] = - log (6.18 x 10-6) = 5.21
6) Cu + 2H2SO4 ---------------> CuSO4 + 2H2O + SO2
As per the balanced reaction 63.5 g of Cu reacts with 2 X 98 g of H2SO4.
therefore 7.1 g of Cu will react with 21.91 g of H2SO4.
Therefore H2SO4 is the limiting reagent
As per the balanced reaction 2 X 98 g of H2SO4 gives 64 g of SO2.
Therefore 6.1 g H2SO4 gives (64 x 6.1)/ 196 = 1.99 g of SO2.
Now 64 g of SO2 occupies 22.4 L at NTP
so 1.99 g will occupy (22.4 x 1.99) / 64 = 0.7 L
6,2 x 10-4 ----------- 0 0 -X +X +X 6,2 x 10-4 -X X XRelated Questions
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