# When 2.25 g of sodium hydroxide (NaOH) was dissolved in 150.00 g of water a value of 11.00oC was obtained for ΔT.1. Calculate the molarity of the sodium hydroxide solution.2. Calculate the value (calories) for the heat of solution of 2.25 g of NaOH.3. Calculate the number of calories that would be produced if one mole of sodium hydroxide was dissolved. (ΔHsolnNaOH)

For 1: The molarity of sodium hydroxide solution is 0.375 M

For 2: The amount of heat absorbed by solution is 1674.75 Cal

For 3: The enthalpy change of the reaction when 1 mole of NaOH is dissolved is 1674.75 Cal

Explanation:

• For 1:

To calculate mass of a substance, we use the equation:

Density of water = 1 g/mL

Mass of water = 150.00 g

Putting values in above equation, we get:

To calculate the molarity of solution, we use the equation:

We are given:

Mass of solute (sodium hydroxide) = 2.25 g

Molar mass of sodium hydroxide = 40 g/mol

Volume of solution = 150.00 mL

Putting values in above equation, we get:

Hence, the molarity of sodium hydroxide solution is 0.375 M

• For 2:

To calculate the amount of heat absorbed, we use the equation:

where,

m = mass of solution = (2.25 + 150) = 152.25 g

c = specific heat capacity of water = 1 Cal/g.°C

= change in temperature = 11°C

Putting values in above equation, we get:

Hence, the amount of heat absorbed by solution is 1674.75 Cal

• For 3:

To calculate the enthalpy change of the reaction, we use the equation:

where,

= amount of heat absorbed = 16

74.75 Cal

n = number of moles = 1 mole

= enthalpy change of the reaction

Putting values in above equation, we get:

Hence, the enthalpy change of the reaction when 1 mole of NaOH is dissolved is 1674.75 Cal

The molarity of the sodium hydroxide is 0.375 M. The heat of solution of the sodium hydroxide is -1650 cal, and the heat of solution per mole of sodium hydroxide is -29333.33 cal/mol.

### Explanation:

To answer your questions, we first need to convert the mass of the sodium hydroxide (NaOH) to moles. Sodium hydroxide has a molar mass of approximately 40 g/mol, so 2.25 g is 0.05625 mol.

1. The molarity of the solution is the number of moles of solute per liter of solution. Given that the solution was made up in 150.00 g of water, which is approximately 0.150 L (since the density of water is approximately 1 g/mL), the molarity is 0.05625 mol / 0.150 L = 0.375 M.

2. The heat of solution can be calculated using the equation q = m * c * ΔT, where m is the mass of the water, c is the specific heat capacity of the water (approximately 1 cal/g°C), and ΔT is the change in temperature. Plugging in the known values, q = 150.00 g * 1 cal/g°C * 11°C = 1650 cal. This is the heat absorbed by the water and so the heat of solution of NaOH is -1650 cal (as the process of dissolving is exothermic).

3. The heat of solution per mole of sodium hydroxide can be calculated by dividing the total heat of solution by the number of moles of sodium hydroxide. So ΔHsoln NaOH = -1650 cal / 0.05625 mol = -29333.33 cal/mol.

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1.01 x 10^-3 moles

g Acetic acid is diluted with water to make a solution of vinegar. You have a sample of vinegar that contains 16.7 g of acetic acid. Determine the number of moles of acetic acid in the vinegar sample.

0.278 mol

Explanation:

Step 1: Given and required data

Mass of acetic acid (m): 16.7 g

Chemical formula of acetic acid: CH₃COOH (C₂H₄O₂)

Step 2: Calculate the molar mass (M) of acetic acid

We will use the following expression.

M(C₂H₄O₂) = 2 × M(C) + 4 × M(H) + 2 × M(O)

M(C₂H₄O₂) = 2 × 12.01 g/mol + 4 × 1.01 g/mol + 2 × 16.00 g/mol = 60.06 g/mol

Step 3: Calculate the number of moles (n) of acetic acid

We will use the following expression.

n = m/M

n = 16.7 g/(60.06 g/mol) = 0.278 mol

Consider the following unbalanced equation for the combustion of hexane: αC6H14(g)+βO2(g)→γCO2(g)+δH2O(g) Part A Balance the equation. Give your answer as an ordered set of numbers α, β, γ, ... Use the least possible integers for the coefficients. α α , β, γ, δ = nothing Request Answer Part B Determine how many moles of O2 are required to react completely with 5.6 moles C6H14. Express your answer using two significant figures. n n = nothing mol Request Answer Provide Feedback

2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O

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αC₆H₁₄ + βO₂ → γCO₂ + δH₂O

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C₆H₁₄ + 9O₂ → 6CO₂ + 7H₂O

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2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O

Problem 2

From the reaction:

2 moles of hexane are required to completely react with 19 moles of O₂

∴ 5.6 moles of hexane would react with k moles of O₂

This gives:     5.6 x 19 = 2k

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