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4 years ago

Find the answer for question c

Chemistry

1 answer:

kipiarov [429]4 years ago

8 0

Phosphorus pentoxide react with sodium hydroxide

P4O10 + 12NaOH → 4Na3PO4 + 6H2O

The salt so formed is called sodium phosphate or trisodium phosphate.

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which sample, when dissolved in 1.0 liter of water, produces a solution with the highest boiling point?

andrew-mc [135]

<span>The correct answer is (C) 0.2 mole MgCl2.

according to Van't Hoff factor rule which is the ratio between the actual

concentration of the particles produced when the substance dissolved and

the concentration of the substance as measured from its mass, so here 0.2

mole MgCl2 is the higher van't Hoff factor as it has more ions than other

choices and the higher concentration.

and when the boiling point formula is delta Tb = Kb * m * i.

when delta Tb is the change in boiling point.

and Kb is molal boiling point constant

and m is the molality of the solution

and i is Van't Hoff factor.

so we can see the relationship between i and delta Tb, the greater Van't Hoff factor the higher the boiling point. so 0.2 MgCl2 is the higher boiling point as it is the greater van't Hoff factor.</span>

4 0

3 years ago

Calculate the amount of water (in grams) that must be added to (a) 6.80 g of urea [(NH2)2CO] in the preparation of a 9.95 percen

Lemur [1.5K]

Explanation:

Amount of water required in each case:

(a)The mass% of the solution is:9.95

Mass of solute that is urea is 6.80 g

To determine the mass of solvent water use the formula:

$mass percent=\frac{mass of solute}{mass of solution} x 100\\\\9.95=(6.80g/mass of solution )x100\\mass of solution =(6.80 /9.95)x100\\=68.3 g$

Hence the mass of solvent = mass of solution - the mass of solute

=68.3 g - 6.80g

=61.5 g

Hence, the answer is mass of solvent water required is 61.5 g.

(b) Given mass%=1.70

mass of solute MgBr2 = 29.3 g

The mass of solvent water required can be calculated as shown below:

$mass percent=\frac{mass of solute}{mass of solution} x 100\\\\1.70=(29.3g/mass of solution )x100\\mass of solution =(29.3 g /1.70)x100\\=1720 g$

The mass of the solution is 1720 g.

Mass of solvent water = mass of solution - mass of solute

=1720 g - 29.3 g

=1690.7 g

Answer: The mass of water required is 1690.7 g.

5 0

3 years ago

The solution to be tested in this experiment must be buffered to ph of 10. If the ph were considerably higher, such as 12, how w

Serhud [2]

For a solution to be tested in this experiment and must be buffered to pH of 10, the [OH-] change will be, The hydroxide concentration would be higher and the formation of insoluble hydroxide salts with Mg^2 and Ca^2 would cause the determined concentration of water hardness to be too low.

<h3>What would be the [OH-] change?</h3>

Generally, the equation for the Total hardness is mathematically given as

$T=\frac{A*D*1000}{B}$

Where

$D=\frac{molarity}{0.01}$

D=0.02/0.01=2

Therefore

$T=\frac{A*D*1000}{B}\\\\T=\frac{20.4*2*1000}{25}$

T=1632ppm

in conclusion, The hydroxide concentration would be higher .