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J-5
SHORT ANSWER
Include all calculation steps and units in your answers to the problems.
(4.0)
13.
(Exp C) A student recorded the following information for the qualitative ion tests on an unknown
hydrate:
A.
cation identified:
barium
B.
anion tests:
i.
The additon on 1.0 mL of 6.0 M HCl to a 1.0 mL aqueous sample of the unknown
hydrate gave NO reaction.
ii.
The additon on 1.0 mL of 6.0 M HCl plus 1 mL of 1.0 M BaCl2 to a 1.0 mL
aqueous sample of the unknown hydrate gave NO reaction.
iii.
The addition of 6 drops of 0.10 M AgNO3 and 1 drop of 6.0 M HNO3, resulted
in the formation of a white precipitate.
a)
Identify the anion present in the hydrate salt? Support your answer with the relevant
balanced net ionic equations for the reactions that result in the formation of the white
precipitate.
A sample of this hydrated salt was dried quantitatively in a crucible to constant mass. The following
data were recorded:
mass of crucible
23.110 g
mass of crucible plus hydrate
25.581 g
mass of crucible plus sample after heating
25.244 g
b)
Calculate the mass percentage of water in the hydrate.
c)
Determine the empirical formula of the hydrate.
(4.0)
14.
(Exp D) For the reaction:
HSO3NH
2(aq)
+ NaNO
2(aq)
NaHSO
4(aq)
+ N
2(g)
+H2O
(l)
determine the masses of HSO3NH2 and
NaNO2 required to produce 0.135 g of N2(g) collected in a
buret above water. Calculate the volume that this mass of N2(g) would occupy at 23.4
C and 7.10 x
10² mm Hg barometric pressure.
