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3 years ago

A 0.69-g sample of lime (CaO) is dissolved in enough water to make 1535 mL of solution. Calculate the pH of of the solution.

Chemistry

1 answer:

Marizza181 [45]3 years ago

4 0

Answer:

pH = 12.2

Explanation:

Given data:

Mass of lime = 0.69 g

Volume = 1535 mL (1535 / 1000 = 1.535 L)

pH of solution = ?

Solution:

First of all we will determine the molarity.

Molarity = moles of solute / volume in litter

Number of moles = mass / molar mass

Number of moles = 0.69 g / 56.1 g/mol

Number of moles = 0.0123 mol

Molarity = moles of solute / volume in litter

Molarity = 0.0123 mol / 1.535 L

Molarity = 0.008 M

One mole of CaO neutralize two mole of OH⁻.

0.008 M×2 = 0.016 M

[OH⁻] = 0.016 M

pOH = -log [OH⁻]

pOH = [0.016]

pOH = 1.8

14 = pH +pOH

pH = 14 - pOH

pH = 14-1.8

pH = 12.2

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When a 0.245-g sample of benzoic acid is combusted in a bomb calorimeter, the temperature rises 1.643 ∘C . When a 0.260-g sample

sveticcg [70]

Answer:

The heat of combustion per moles of caffeine is 4220 kJ/mol

Explanation:

Step 1: Data given

⇒ When benzoic acid sample of 0.245 grams is burned the temperature rise is 1.643 °C

⇒ When 0.260 gram of caffeine is burned, the temperature rise is 1.436 °C

⇒ Heat of combustion of benzoic acid = 26.38 kJ/g

Step 2: Calculate the heat released: for combustion of benzoic acid

0.245 g benzoic acid * 26.38 kJ/g = 6.4631 kJ

Step 3: Calculate the heat capacity of the calorimeter:

c = Q/ΔT

Q = 6.4631 kJ / 1.643°C = 3.934 kJ/ °C

Step 4: Calculate moles of a 0.260 g sample of caffeine:

Moles caffeine = Mass caffeine / Molar mass caffeine

0.260 grams/ 194.19 g/mol = 0.0013389 moles

Step 5: Calculate heat released: for combustion of caffeine

Q = c * ΔT

Q = 3.934 kJ/°C * 1.436 °C = 5.65 kJ

Step 6: Calculate the heat of combustion per mole of caffeine

5.65 kJ / 0.0013389 moles = 4219.9 kJ/mol ≈ 4220 kJ/mol

The heat of combustion per moles of caffeine is 4220 kJ/mol

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4 years ago

Describe how you would use a calorimeter to determine the specific heat capacity of a metal

vovikov84 [41]

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3 years ago

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What does the number next to ions signify?

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3 years ago

You and your lab group have been asked to design an investigation to determine the effects of heat transfer between two differen

GREYUIT [131]

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3 years ago

The rate law for the decomposition of phosphine () is It takes 135. s for 1.00 M to decrease to 0.250 M. How much time is requir

vova2212 [387]

Answer:

189.71 secs

Explanation:

We know that decomposition is a first order reaction;

So;

ln[A] = ln[A]o - kt

But;

[A]o = 1.00 M

[A] = 0.250 M

t =135 s

Hence;

ln[A] - ln[A]o = kt

k = ln[A] - ln[A]o/t

k = ln(1) - ln(0.250)/135

k =0 - (-1.386)/135

k = 1.386/135

k= 0.01

So time taken now will be;

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t = ln[A] - ln[A]o/k

t = ln (3) - ln(0.450)/0.01

t = 1.0986 - (-0.7985)/0.01

t = 1.0986 + 0.7985/0.01

t = 189.71 secs

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3 years ago