I am trying to calculate my percent error for an experiment conducted. I need to compare my average density calculated to the accepted average density but I am having trouble doing this because of the conversions.
My average density was 0.12 g/mm^3. The accepted value is for iron which is 7.8 X 10^3 kg/m^3.
So to get 0.12 g to kg I multiplied by 1000 and got 120.
Then I subtracted 120 from 7.80 X 10^3.
Is this correct so far??
You got it backwards:
0.12kg is 120g
0.12g = 0.00012kg
.12g * 1kg/1000g = .00012kg
Oops. Forgot to include the volume:
.12g/mm^3 * 1kg/1000g * 1m^3/(1000mm)^3 = 120000kg/m^3
Oh ok so now to find the percent error do I subtract 120,000 from 7800 and then multiply by 100?
well, if the correct value is 10, and you get 12, then the percent error is (12-10)/10 * 100 = 20%
Yours is figured the same way, but the values are so different, I wonder whether there is something wrong here.
Yes my data is probably wrong I'm just not sure where I messed up
To calculate percent error, you need to follow a specific formula:
Percent Error = [(|Experimental Value - Accepted Value|) / Accepted Value] * 100
Let's work through the calculation step by step.
1. Start with your average density: 0.12 g/mm^3.
2. Since the accepted value is given in kg/m^3, you need to convert your average density to kg/m^3. To do this, you multiply 0.12 g/mm^3 by (1 kg / 1000 g) to convert grams to kilograms and (1000 mm / 1 m)^3 to convert cubic millimeters to cubic meters.
0.12 g/mm^3 * (1 kg / 1000 g) * (1000 mm / 1 m)^3 = 0.12 kg/m^3 * (1 / 1,000,000) = 1.2 x 10^-4 kg/m^3
Therefore, your converted average density is 1.2 x 10^-4 kg/m^3.
3. Now you can calculate the percent error using the formula mentioned above:
Percent Error = [(|Experimental Value - Accepted Value|) / Accepted Value] * 100
Percent Error = [|1.2 x 10^-4 kg/m^3 - 7.8 x 10^3 kg/m^3| / 7.8 x 10^3 kg/m^3] * 100
To simplify the calculation, we can write it as:
Percent Error = (|1.2 x 10^-4 - 7.8 x 10^3| / 7.8 x 10^3) * 100
4. Continue with the subtraction inside the absolute value:
Subtracting 7.8 x 10^3 from 1.2 x 10^-4, we get:
1.2 x 10^-4 - 7.8 x 10^3 = -7.79988 x 10^3
Now we can plug these values back into the percent error formula:
Percent Error = (|-7.79988 x 10^3| / 7.8 x 10^3) * 100
5. Lastly, calculate the value inside the absolute value:
|-7.79988 x 10^3| = 7.79988 x 10^3
Plugging this value into the percent error formula:
Percent Error = (7.79988 x 10^3 / 7.8 x 10^3) * 100
Simplifying it further:
Percent Error = 99.9989%
Therefore, the percent error in your calculation is approximately 99.9989%.