Question

ANSWER ALL QUESTIONS!!

16 A certain salt has a molar solubility of 1.0X 104 moles/liter. The molar mass of this salt is 240 grams/mole. What mass of this salt will dissolve in 1 liter of water? A 240g B 24.4g C 2.4g D 0.24g E 0.024g F 2.4 X 10-ºg G 2.4 X 104g 17 What is the pH of a 0.1M weak monoprotic acid, HA, whose Ka= 10-5 HA(aq) <-> H+(aq) + A'(aq) A 1.0 B 2.0 C 3.0 D 4.0 E 5.0 F 7.0 G 11.0 H-5 18 A student used a dirty test tube to measure the freezing point of Lauric acid. The dirt in the test tube dissolved in the Lauric acid. This student's measured freezing point temperature of Lauric acid will be the true freezing point. A lower than B higher than C the same as 19 What is the concentration of hydroxide ions in stomach acid that has a pH of 2 A 10-2M B 10-10M C 10-12M D2M E 12M F102M

Answer 1

16)

option E

MOLAR SOLUBILITY GIVEN = 0.0001 mol/L

Molar mass = 240 g/mol

the solubilty of salt in grams/L = 240 g * 0.0001 mol

= 0.0240 g

0.0240 g of salt is dissolved in 1 liter of water.

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17)

option A

pH is the negative logarthim of hydrogen ion concentration.

$pH=-log[H^{+}]$

= -log[10-

  

= -(-1)log[10

$=+log[10]$

$=1$

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18)

option A

The dirt is non volatile solute.

lauric acid is pure solvent

when dirt is added to pure solvent like lauric acid here , there will be a change in COLLIGATIVE PROPERTY. The freezing point is depressed.

The freezing point is lowered.

The freezin gpoint of contaminated lauric acid will be lower than that of pure lauric acid.

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19) option C

pH is the negative logarthim of hydrogen ion concentration.

$pH=-log[H^{+}]$

$2=-log[H^{+}]$

So,

   

But ionic product of water , Kw =

$Kw=[H^{+}][OH^{-1}]$

But, $Kw=1*10^{-14}$

$[OH^{-1}] =\frac{1.0*10^{-14}}{10^{-2}}$

= $1.0*10^{-12}$