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3 years ago

A sample of an ionic compound NaA, where A- is the anion of a

Chemistry

1 answer:

vitfil [10]3 years ago

6 0

Answer:

a) Kb = 10^-9

b) pH = 3.02

Explanation:

a) pH 5.0 titration with a 100 mL sample containing 500 mL of 0.10 M HCl, or 0.05 moles of HCl. Therefore we have the following:

[NaA] and [A-] = 0.05/0.6 = 0.083 M

Kb = Kw/Ka = 10^-14/[H+] = 10^-14/10^-5 = 10^-9

b) For the stoichiometric point in the titration, 0.100 moles of NaA have to be found in a 1.1L solution, and this is equal to:

[A-] = [H+] = (0.1 L)*(1 M)/1.1 L = 0.091 M

pKb = 10^-9

Ka = 10^-5

HA = H+ + A-

Ka = 10^-5 = ([H+]*[A-])/[HA] = [H+]^2/(0.091 - [H+])

[H+]^2 + 10^5 * [H+] - 10^-5 * 0.091 = 0

Clearing [H+]:

[H+] = 0.00095 M

pH = -log([H+]) = -log(0.00095) = 3.02

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Explain what the name scandium lll oxide means in terms of electrons lost and gained and identify the correct formula

andre [41]

Scandium lost 3 electrons and gave them to oxygen the formula would be Sc2O3

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3 years ago

During the following chemical reaction, 46.3 grams of C3H6O react with 73.2 grams of O2

ra1l [238]

Answer:

a) O2 is the limiting reactant

b) 75.70 grams CO2 (theoretical yield)

c) There remains 12.81 grams of C3H6O

d) The actual yield CO2 is 34.29 grams

Explanation:

Step 1: Data given

Mass of C3H6O = 46.3 grams

Mass of O2 = 73.2 grams

Molar mass of C3H6O = 58.08 g/mol

Molar mass of O2 = 32 g/mol

Step 2: The balanced equation

C3H6O + 4O2 → 3 CO2 + 3H2O

Step 3: Calculate moles C3H6O

Moles C3H6O = mass C3H6O / molar mass C3H6O

Moles C3H6O = 46.3 grams / 58.08 g/mol

Moles C3H6O = 0.793 moles

Step 4: Calculate moles O2

Moles O2 = 73.2 grams / 32 g/mol

Moles O2 = 2.29 moles

Step 5: Calculate limiting reactant

For 1 mol C3H6O we need 4 moles of O2 to produce 3 moles CO2 and 3 moles H2O

O2 is the limiting reactant. It will completely be consumed. (2.29 moles).

C3H6O is in excess. There will react 2.29/4 = 0.5725 moles C3H6O

There will remain 0.793 - 0.5725 = 0.2205 moles C3H6O

This is 0.2205 moles * 58.08 g/mol = 12.81 grams

Step 6: Calculate moles of CO2

For 1 mol C3H6O we need 4 moles of O2 to produce 3 moles CO2 and 3 moles H2O

For 2.29 moles O2 we need 3/4 * 2.29 = 1.72 moles CO2

This is 1,72 moles * 44.01 g/mol = 75.70 grams CO2

Step 7: Calculate actual yield

% yield = 45.3 % = 0.453 = (actual yield / theoretical yield)

actual yield = 0.453 * 75.70 = 34.29 grams

3 0

3 years ago

When ammonium chloride is added to water and stirred, it dissolves spontaneously and the resulting solution feels cold. Without

d1i1m1o1n [39]

When ammonium chloride NH4Cl is added to water and stirred, it dissolves spontaneously (this is the basis for ΔG) for and the resulting solution feels cold (endothermic, the basis for ΔH). Without doing any calculations, we can easily deduce the signs of ΔG, ΔH, and ΔS for this process based on the observations.

ΔG < 0 (it is spontaneous)
ΔH < 0 (because the process is endothermic - it absorbs energy)
ΔS > 0 (entropy increases because of the dissolution of NH4Cl in water

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2 years ago

What type of potential energy do fuels contain

NISA [10]

Kinetic energy maybe or something

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3 years ago

Read 2 more answers

In a laboratory experiment, students synthesized a new compound and found that when 7.229 grams of the compound were dissolved i

STALIN [3.7K]

The question is incomplete, here is the complete question:

The common laboratory solvent chloroform is often used to purify substances dissolved in it. The vapor pressure of chloroform, CHCl₃, is 173.11 mm Hg at 25°C.

In a laboratory experiment, students synthesized a new compound and found that when 7.229 grams of the compound were dissolved in 207.8 grams of chloroform, the vapor pressure of the solution was 170.51 mm Hg. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight of this compound?

Answer: The molecular mass of the compound is 481.9 g/mol

Explanation:

The equation used to calculate relative lowering of vapor pressure follows:

$\frac{p^o-p_s}{p^o}=i\times \chi_{solute}$