The image above represents the weight average molecular weight. Two essential parameters are needed to calculate the average molecular weight: weight fraction (W) and arithmetic mean of the molecular mass distribution (M).
The formula for calculating the weight average molecular weight:
Mw = ΣWM
Where;
Mw = Weight Average Molecular Weight
W = Weight Fraction
M = Arithmetic Mean of the Molar Mass Distribution
Let’s solve an example;
Find the weight average molecular weight when the weight fraction is 9 and the arithmetic mean of the molar mass distribution is 18.
This implies that;
W = Weight Fraction = 9
M = Arithmetic Mean of the Molar Mass Distribution = 18
Mw = ΣWM
| W | M | WM |
|---|---|---|
| 9 | 18 | 162 |
ΣWM = 162
ΣWM = 162
Mw = 162
Therefore, the weight average molecular weight is 162.
Calculating the Weight Fraction when the Weight Average Molecular Weight and the Arithmetic Mean of the Molar Mass Distribution are Given
W = Mw / M
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Where;
W = Weight Fraction
Mw = Weight Average Molecular Weight
M = Arithmetic Mean of the Molar Mass Distribution
Let’s solve an example;
Find the weight fraction when the weight average molecular weight is 27 and the arithmetic mean of the molar mass distribution is 14.
This implies that;
Mw = Weight Average Molecular Weight = 27
M = Arithmetic Mean of the Molar Mass Distribution = 14
So, W = Mw / M
W = 27 / 14
W = 1.928
Therefore, the weight fraction is 1.928
Read more:Â How to Calculate and Solve for Molecular Weight of Homopolymer | Polymer & Textile
Calculating the Weight Fraction when the Weight Average Molecular Weight and the Arithmetic Mean of the Molar Mass Distribution are Given
M = Mw / W
Where;
M = Arithmetic Mean of the Molar Mass Distribution
Mw = Weight Average Molecular Weight
W = Weight Fraction
Let’s solve an example;
Find the arithmetic mean of the molar mass distribution when the weight fraction is 120 and the weight average molecular weight is 340.
This implies that;
Mw = Weight Average Molecular Weight = 340
W = Weight Fraction = 120
Then, M = Mw / W
M = 340 / 120
M = 2.83
Therefore, the arithmetic mean of the molar mass distribution is 2.83.
How to Calculate Weight Average Molecular Weight Using Nickzom Calculator
Nickzom Calculator – The Calculator Encyclopedia is capable of calculating the sum of weight average molecular weight.
To get the answer and workings of the weight average molecular weight using the Nickzom Calculator – The Calculator Encyclopedia. First, you need to obtain the app.
You can get this app via any of these means:
Web – https://www.nickzom.org/calculator-plus
To get access to the professional version via web, you need to register and subscribe for NGN 1,500 per annum to have utter access to all functionalities.
You can also try the demo version via https://www.nickzom.org/calculator
Android (Paid) – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator
Android (Free) – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator
Apple (Paid) – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8
Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Polymer & Textile under Engineering.
Now, Click on Weight Average Molecular Weight under Polymer & Textile
The screenshot below displays the page or activity to enter your values, to get the answer for the weight average molecular weight according to the respective parameters which are the Weight Fraction (W) and Arithmetic Mean of the Molar Mass Distribution (M).
Now, enter the values appropriately and accordingly for the parameters as required by the Weight Fraction (W) is 9 and Arithmetic Mean of the Molar Mass Distribution (M) is 18.
Finally, Click on Calculate
As you can see from the screenshot above, Nickzom Calculator– The Calculator Encyclopedia solves for the weight average molecular weight and presents the formula, workings and steps too.
