Is this how you would draw Lewis structure for NO2?
1 answer:
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Answer:
The mass percentage of the solution is 10.46%.
The molality of the solution is 2.5403 mol/kg.
Explanation:
A bottle of wine contains 12.9% ethanol by volume.
This means that in 100 mL of solution 12.9 L of alcohol is present.
Volume of alcohol = v = 12.9 L
Mass of the ethanol = m
Density of the ethanol ,d=
Mass of water = M
Volume of water ,V= 100 mL - 12.9 mL = 87.1 mL
Density of water = D=1.00 g/mL
Mass percent
Molality :
M = 87.1 g = 0.0871 kg (1 kg =1000 g)
The given question is incomplete. The complete question is as follows.
A solution contains an unknown mass of dissolved barium ions. When sodium sulfate is added to the solution, a white precipitate forms. The precipitate is filtered and dried and then found to have a mass of 212 mg. What mass of barium was in the original solution? (Assume that all of the barium was precipitated out of solution by the reaction.)
Explanation:
When and
are added then white precipitate forms. And, reaction equation for this is as follows.
It is given that mass (m) is 212 mg or 0.212 g (as 1 g = 1000 mg). Molecular weight of is 233.43.
Now, we will calculate the number of moles as follows.
No. of moles = mass × M.W
=
= 0.00091 mol of
Hence, it means that 0.00091 mol of . Now, we will calculate the mass as follows.
Mass = moles × MW
=
= 0.124 grams or 124 mg of barium
Thus, we can conclude that mass of barium into the original solution is 124 mg.
Answer:
D. -120.9 kJ
Explanation:
According to Hess's law ,the total enthalpy change for a reaction is the sum of all changes regardless of the stages or the steps of the reaction.
....(1)
(this reaction should be reversed in order to reach the required reaction )
On reversing the reaction the sign of get reversed.
(In this case change sign from '-' to'+'. Hence = + 65 kJ)
....(1)
......(2)
Adding equation (1) and (2)
(It is nearly equal to -120.9 kJ)