A 25.0 mL sample of 0.25 M potassium carbonate (K2CO3) solution is added to 30.0 mL of a 0.40 M barium nitrate (Ba(NO3)2) solution. What is the concentration of the excess metal ion after the precipitation reaction is complete

Respuesta :

Answer:

0.10M of Ba²⁺ is the concentration of the metal in excess

Explanation:

Based on the chemical reaction:

K₂CO₃(aq) + Ba(NO₃)₂(aq) → BaCO₃(s) + 2KNO₃(aq)

1 mole of potassium carbonate reacts per mole of barium nitrate

To solve this question we need to find the moles of each salt to find then the moles of Barium in excess:

Moles K₂CO₃:

0.025L * (0.25mol / L) = 0.00625moles K₂CO₃ = moles CO₃²⁻

Moles Ba(NO₃)₂:

0.030L * (0.40mol/L) = 0.012 moles of Ba(NO₃)₂ = 0.012 moles of Ba²⁺

That means moles of Ba²⁺ that don't react are:

0.012 mol - 0.00625mol = 0.00575 moles Ba²⁺

In 25 + 30mL = 55mL:

0.00575 moles Ba²⁺ / 0.055L =

0.10M of Ba²⁺ is the concentration of the metal in excess

The concentration of the excess metal ion after the precipitation reaction is complete is 0.1045 M

From the question,

We are to determine the concentration of the excess metal ion after the precipitation reaction is complete

First, we will write the balanced chemical equation for the reaction

The balanced chemical equation for the reaction is

K₂CO₃ + Ba(NO₃)₂ → BaCO₃ + 2KNO₃

This means

1  mole of K₂CO₃ is required to react completely with 1 mole of Ba(NO₃)₂

Now, we will determine the number of moles of each reactant present.

  • For K₂CO₃

Volume = 25.0 mL = 0.025 L

Concentration = 0.25 M

Using the formula

Number of moles = Concentration × Volume

∴ Number of moles of K₂CO₃ present = 0.25 × 0.025

Number of moles of K₂CO₃ present = 0.00625 mole

  • For Ba(NO₃)₂

Volume = 30.0 mL = 0.03 L

Concentration = 0.40 M

∴ Number of moles of Ba(NO₃)₂ present = 0.40 × 0.03

Number of moles of Ba(NO₃)₂ present = 0.012 mole

Since

1 mole of K₂CO₃ is required to react completely with 1 mole of Ba(NO₃)₂

Then,

The 0.00625 mole of K₂CO₃ will react with 0.00625 mole of Ba(NO₃)₂

∴ Only 0.00625 mole of the Ba(NO₃)₂ will react

This means Ba(NO₃)₂ is the excess reactant.

Now, we will determine the number of moles of Ba(NO₃)₂ remaining

Number of moles of Ba(NO₃)₂ remaining = 0.012 mole - 0.00625 mole

Number of moles of Ba(NO₃)₂ remaining = 0.00575 mole

Now, for the concentration

Using the formula

[tex]Concentration = \frac{Number\ of\ moles}{Volume}[/tex]

Volume = Total volume of the solution = 0.025L + 0.03L

Volume = 0.055 L

∴ Concentration of the excess metal ion = [tex]\frac{0.00575}{0.055}[/tex]

Concentration of the excess metal ion = 0.1045 M

Hence, the concentration of the excess metal ion after the precipitation reaction is complete is 0.1045 M

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