![]() You need to know the molar mass of the substance. I suppose that a problem can be worded in such a way that the number of grams comes after the unit, but that type of trickery isn't very common in high school. Common abbreviations for grams include g (just the letter) and gm. The number immediately preceeding it will be how many grams. The problem will tell you how many grams are present. Let it be simply the letter "x." The proper unit shouldwill evolve naturally from solving the proportion and cancellation of units.Įxample #1: Convert 25.0 grams of KMnO 4 to moles. Also, do not attach units to the unknown. When you solve a particular problem, you insert the proper numbers & units into the proper places of the symbolic equation and then you solve using cross-multiplication and division. Then the "x" will reside in the upper left. The exact same proportion is used in the moles-to-grams conversion lesson. In this particular lesson, the moles of the substance (lower left) will be the unknown (which will be signified by the letter x). The solution technique can also be expressed in the following ratio and proportion: Make sure you have a periodic table and a calculator handy. Calculate the molar mass of the substance. ![]() Determine how many grams are given in the problem. ![]() There are three steps to converting grams of a substance to moles. So the problem is that, while we compare amounts of one substance to another using moles, we must also use grams, since this is the information we get from balances. However, balances DO NOT give readings in moles. In chemistry, the mole is the standard measurement of amount.
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