Answer is: molality of urea is 5.84 m.
If we use 100 mL of solution:
d(solution) = 1.07 g/mL.
m(solution) = 1.07 g/mL · 100 mL.
m(solution) = 107 g.
ω(N₂H₄CO) = 26% ÷ 100% = 0.26.
m(N₂H₄CO) = m(solution) · ω(N₂H₄CO).
m(N₂H₄CO) = 107 g · 0.26.
m(N₂H₄CO) = 27.82 g.
1) calculate amount of urea:
n(N₂H₄CO) = m(N₂H₄CO) ÷ M(N₂H₄CO).
n(N₂H₄CO) = 27.82 g ÷ 60.06 g/mol.
n(N₂H₄CO) = 0.463 mol; amount of substance.
2) calculate mass of water:
m(H₂O) = 107 g - 27.82 g.
m(H₂O) = 79.18 g ÷ 1000 g/kg.
m(H₂O) = 0.07918 kg.
3) calculate molality:
b = n(N₂H₄CO) ÷ m(H₂O).
b = 0.463 mol ÷ 0.07918 kg.
b = 5.84 mol/kg.
Answer:
The equations are
1) 
2) 
Explanation:
There are two ionization steps in the dissociation of hydroselenic acid.
In first dissociation the H₂Se loses one proton and forms hydrogen selenide ion as shown below:

The next step is again removal of a proton from the base formed above.

It is going to be too low because the mass mistakenly used is lower than the initial.
Answer:
Explanation:
In 150 ml of .06 g / ml solution , gram of iodine = 150 x .06 g = 9 g
Let volume of given concentration of .12 g / ml required be V
In volume V , gram of iodine = V x .12 g
According to question
V x .12 = 9 g
V = 9 / .12 = 75 ml
So, 75 ml of .12 g/ml will be taken and it is diluted to the volume of 150 ml to get the solution of required concentration .
The ratio of moles of reactants to moles of products can be seen from the coefficients in a balanced equation. In our case 4 moles of hydrochloric acid reacts with one mole of oxygen to produce two moles of chlorine and water. So, <span> the ratio of moles of hydrochloric acid to moles of chlorine is 2:1. To determine the number moles, divide the mass by the mass of one mole. </span>
<span>Cl2 = 2 * 35.45 = 70.9 grams </span>
<span>Number of moles = 335 ÷ 70.9 </span>
<span>This is approximately 4.72 moles. The number of moles of hydrochloric acid is twice this number. </span>
<span>Mass of one mole = 1 + 35.46 = 36.45 grams </span>
<span>Total mass = 2 * (335 ÷ 70.9) * 36.45 </span>
<span>This is approximately 344.45 grams.
Correct answer A.</span>