# Titration Exam Question 1: Calculating Concentration of Undiluted Nitric Acid

• IDK10
In summary: But what does this tell you about the undiluted concentration?Well, it's still very high, but not more than a million times higher than before. In summary, the undiluted concentration of nitric acid is 40.2192 g dm-3.
IDK10
1. The problem statement, "all variables and given/known data
A solution of nitric acid, HNO3, of concentration 100 g dm-3, can be used to artificially age wood.

A sample of nitric acid was tested by pipetting 10.00 cm3 of the acid into a 250 cm3 volumetric flask and filled up with deionised water to the mark. A titration took place where 19.95 cm3 (mean titre) of sodium hydroxide solution with a concentration of 0.0800 mol dm-3 was added to 25 cm3

Calculate the concentration of the undiluted nitric acid in g dm-3

MaVa = MbVb

## The Attempt at a Solution

Using the above equation I got the concentration of the 25 cm3 of nitric acid solution as 0.6384mol dm-3, which is 40.2192g dm-3, but how do I find the undiluted concentration?

IDK10 said:
1. The problem statement, "all variables and given/known data
A solution of nitric acid, HNO3, of concentration 100 g dm-3, can be used to artificially age wood.

A sample of nitric acid was tested by pipetting 10.00 cm3 of the acid into a 250 cm3 volumetric flask and filled up with deionised water to the mark. A titration took place where 19.95 cm3 (mean titre) of sodium hydroxide solution with a concentration of 0.0800 mol dm-3 was added to 25 cm3
×
Calculate the concentration of the undiluted nitric acid in g dm-3

MaVa = MbVb

## The Attempt at a Solution

Using the above equation I got the concentration of the 25 cm3 of nitric acid solution as 0.6384mol dm-3, which is 40.2192g dm-3, but how do I find the undiluted concentration?

Well firstly you will need to get into the habit for all quantitative work of checking automatically for order-of-magnitude reasonableness, so some mistakes hit you in the eye. You've taken some almost 0.1 M NaOH, you've neutralised it with a roughly equal volume of acid, and you say the acid is 6× as concentrated! It's a decimal point error, but you home in on detecting it faster by the above type of reasoning than by going through the calculations in detail. And if this is happening in the last 30 seconds of an exam you just write "this figure is unreasonable, about an order of magnitude too high" and you would in this case get most of the credit, at least if it's humans marking.

After you've done that you have the concentration of your diluted nitric acid. You had diluted this 25× and you ask what was the original concentration?

berkeman
Just redid the equation and got values ten times smaller than before, so its 4.02192 g dm-3 for the 25 cm3 for the acid used. So, x25 now?

Yes

## 1. What is a titration exam question?

A titration exam question involves determining the concentration of an unknown solution by reacting it with a known solution of a different concentration. This process is used to find the endpoint of a reaction and calculate the unknown concentration.

## 2. What are the key components of a titration exam question?

The key components of a titration exam question include the known concentration and volume of the solution used, the unknown concentration and volume of the solution being titrated, and the reaction equation between the two solutions. Additionally, the question may include information about the indicator used and any necessary calculations.

## 3. How do you solve a titration exam question?

To solve a titration exam question, you must first write out the balanced reaction equation and determine the mole ratio between the known and unknown solutions. Then, using the volume and concentration information, you can calculate the number of moles of the known solution used. From there, you can use the mole ratio to determine the number of moles of the unknown solution and calculate its concentration.

## 4. What are some common mistakes to avoid when solving a titration exam question?

Some common mistakes to avoid when solving a titration exam question include using the wrong mole ratio, forgetting to account for the volume change when combining the two solutions, and misinterpreting the endpoint of the titration. It is important to carefully read the question and double check your calculations to avoid these errors.

## 5. How can I practice solving titration exam questions?

The best way to practice solving titration exam questions is to work through practice problems and past exams. You can also find online resources and videos that explain the process and provide step-by-step examples. Additionally, you can try setting up your own titration experiments in a lab to gain hands-on experience.

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