### All High School Chemistry Resources

## Example Questions

### Example Question #1 : Analytical Chemistry

Robert conducted an experiment in which he investigated how much water a paper towel could absorb. Initially, Robert found that one paper towel can absorb 12.8g of water. Later he found that his scale was not calibrated, so he had to repeat the experiment. After repeating the experiment with a new scale, Robert found that one paper towel can actually absorb 32.9g of water. What is the approximate percent error between the findings of the first and second experiments?

**Possible Answers:**

**Correct answer:**

The formula for percent error is:

In this case, the measured value is 12.8g and the accepted value is 32.9g.

### Example Question #1 : Precision, Accuracy, And Error

A reaction between one mole of sodium and one mole of chloride should yield 42 grams of sodium chloride. In your experiment, the actual yield is 32.73 grams. Calculate the percent error of your experiment.

**Possible Answers:**

**Correct answer:**

To find percent error we need to use the following equation:

Plug in 42 for the theoretical yield and 32.73 for the actual yield and solve accordingly.

### Example Question #1 : Analytical Chemistry

In the following reaction, eight moles of sodium hydroxide is broken down into four moles of sodium oxide and four moles of water. What is the percent error if your experiment yields 195 grams of sodium oxide?

**Possible Answers:**

**Correct answer:**

To find the percent error we need to use the following equation:

But in order to do this, we first have to convert moles of sodium oxide into grams:

This gives us a theoretical yield of 248g, which we plug in with our 195g actual yield.

### Example Question #1 : Calculating Error

If a given sample of silver and flourine ideally combine to form 0.6mol of AgF, what is the percent error if the actual yield is 43 grams?

**Possible Answers:**

**Correct answer:**

Our first step to complete this problem is to convert moles AgF into grams:

This gives us a theoretical yield of 76.2 grams. We can find the percent error by plugging in 76.2g for our theoretical yield and 43g for the actual yield in the following equation:

### Example Question #1 : Calculating Error

After conducting an experiment that involved the reaction of solutions of and , 6.8 grams of was yielded. What is the percent error if the theoretical yield of for this experiment is 7.8 grams?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

### Example Question #1 : Precision, Accuracy, And Error

A student measures that a piece of string is 2.6 cm, but the actual length of the string is 2.9 cm. What is the student's percent error?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

### Example Question #1 : Calculating Error

A standard mass of 100.0 grams was placed on a balance. The balance indicated that the mass was 101.6 grams. What is the percent error for the balance?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

### Example Question #1 : Calculating Error

From an experiment, a student found the density of a rubber eraser was . However, the actual density of the eraser is . What is the student's percent error?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

### Example Question #1 : Calculating Error

The experimental value obtained for the specific heat of gold was . The known specific heat of gold is . What is the percent error?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

### Example Question #6 : Precision, Accuracy, And Error

A reaction produced 98.5 grams of nitrogen dioxide gas. However, the calculated theoretical value indicates that 115.2 grams of nitrogen dioxide gas should have been produced. What is the percent error?

**Possible Answers:**

**Correct answer:**

Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.