Molar Mass

[Coraly De Leon]

Hello,
Does anyone know if it is safe to always assume 100 g when calculating for a molecular formula, in the case of the gram amount not being given ?

[Trisha Mantri 3L]

Yes, unless there is an explicit amount given, always use 100g, as it makes percent composition problems much easier to solve.

[Madison Kiggins 1E]

Yes, I believe it is always safe to use 100 g unless there is a specific amount given. This makes it easier as we can simply use the mass percent composition to solve for both molecular and empirical equations.

[Jocelyn Chin 1K]

Yes; we assume 100g because percentages are easy to calculate since the definition of percentage is a number/100. Molecular formula comes from empirical formula, and we calculate empirical formula from the ratio of atoms in a compound. It's easiest to find these ratios when you divide things by 100 and assume 100 grams. You can also assume 200 grams or 700 grams, but then calculating would require a lot of unnecessary effort.

[305597516]

Yes, this is acceptable, since you already know the molar mass percentages in this context.

[Katryn Heine 3A]

Yes it's acceptable. It's just an easier way of unit conversion.

[tristenleem3B]

Yes, unless specified otherwise it makes the calculation to percentage simple.

[405532435]

Yes! Dr. Lavelle told us to assume 100g if it is not previously stated. Hope this helps!

[Dillon Taing 3H]

Yes, if there is no specified amount, using 100g to find the molecular formula simplifies the process.

[Palig Kechichian 3F]

Yes, because you already know that a percentage implies your given value /100, and if you're given a percentage mass composition, then each value would in turn be out of 100 g

[jordancha3I]

It should always be safe to use 100g, this is assuming that nothing else is previously stated. It also makes calculating percentage composition easier.

[Chris Van 2J]

Hi there, 100g is always the best conversion to use!

[Amy Shimizu 1J]

Yes, you should always use 100 g when finding the molecular formula if the mass is not given! Dr. Lavelle mentioned this in his lecture as well, since using 100 g as the mass makes it a lot easier to calculate, especially if you are given the percent mass.

[Anish_Marripati_2F]

We should always use 100g when there isn't a specific mass or value associated with the elements in the given problem.

[Maia Holmes Kueny 1C]

Yes, unless there is an amount given.

[Luke Schwuchow 14A]

Honestly, you could use any number or value when determining this. However, we usually stick to 100 grams because it is the easiest when calculating. Instead of finding 26% of 52g of a compoud is made of carbon by mass, we would find 26% of 100. It just makes the whole calculation simpler.

[dahlia Faruque]

Yes, it is always safe to use 100g because it makes calculating the percentage easier when calculating the molar mass of elements.

[Ashley Fakolujo 3H]

Yes, Professor actually encouraged this in the beginning of the quarter when we were learning how to find it