# Determining Initial and Equilibrium Concentration (Help )

• galaticman
In summary, the conversation discusses the process of determining the initial and equilibrium concentrations of Fe3+ and SCN- in a solution. The experiment involves mixing 10 mL of 2.0x10-3 M Fe(NO3)3 and 2 mL of 2.0x10-3 M NaSCN in a total volume of 50 mL. The key is to calculate the initial SCN- concentration and assume that all of it is present as FeNCS2+. The experts suggest finding the moles of SCN- in 2 mL and determining the concentration in a 50 mL volume. It is also mentioned that the presence of NaSCN is irrelevant for the problem.
galaticman
Determining Initial and Equilibrium Concentration (Help!)

## Homework Statement

You are given the equation Fe3+ + SCN- -> FeSCN-
You are performing an experiment in which you are mixing Fe(NO3)3 and NaSCN. A table is given and I will only list the first sets of data because if i can figure out the process for the first one I can figure out the rest. The table is:

10 mL of 2.0x10-3 M Fe(NO3)3
2mL of 2.0x10-3
Total Volume of Solution: 50mL

You are asked to to calculate the initial SCN- concentration (M) as well as the equilibrium FeNCS2+ concentration (M)

I am just not sure how to go about doing that. Any help would be greatly appreciated!

NOTE: It also mentions that to assume all of the SCN- is present as FeNCS2+ but I am pretty sure that this is irrelevant and is relevant to the later part of the lab

So, if I understand you correctly, you take 2 mL of 2x10-3M solution of SCN-, and you dilute it up to 50 mL (other solution doesn't matter at this moment)?

How many moles of SCN- in these 2 mL? What is the concentration of the solution containing this amount of SCN- in a 50 mL volume?

Yup that is pretty much it except it is not just SCN it is NaSCN but I am not sure if that matters for the problem or not?

It doesn't matter - if the solution is 2x10-3 M in NaSCN, it is also 2x10-3 M in Na+ and SCN-.

Ohhhh okay I got it then! Thanks!

## What is the purpose of determining initial and equilibrium concentration?

The purpose of determining initial and equilibrium concentration is to understand the extent and rate of a chemical reaction. This information is crucial in predicting the behavior of a reaction and its products, as well as in determining the most efficient conditions for the reaction to occur.

## How do you calculate initial and equilibrium concentrations?

To calculate initial concentrations, you need to know the amount of each reactant present at the beginning of the reaction. This can be measured directly or calculated using stoichiometry. Equilibrium concentrations can be calculated using the equilibrium constant, which takes into account the concentrations of all reactants and products at equilibrium.

## What factors can affect initial and equilibrium concentrations?

Several factors can affect initial and equilibrium concentrations, including temperature, concentration of reactants and products, pressure, and catalysts. These factors can alter the rate of the reaction and shift the equilibrium position, ultimately changing the concentrations of reactants and products at equilibrium.

## How can you experimentally determine initial and equilibrium concentrations?

To determine initial and equilibrium concentrations experimentally, you need to measure the concentrations of reactants and products at different time points during the reaction. This can be done by taking small samples of the reaction mixture and analyzing them using techniques such as spectrophotometry or titration. By plotting the concentrations over time, you can determine the initial and equilibrium concentrations.

## What is the significance of initial and equilibrium concentrations in a chemical reaction?

Initial and equilibrium concentrations provide important information about the progress and behavior of a chemical reaction. They allow us to predict the direction of a reaction, understand the factors that affect its rate, and determine the most efficient conditions for the reaction to occur. In addition, they help us to calculate equilibrium constants, which can provide insights into the thermodynamics of the reaction.

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