For each of the following ionic substances, calculate the percentage of the overall molar mass o

For each of the following ionic substances, calculate the...

Key Concepts

Ionic Compounds

Ionic compounds are chemical compounds composed of positively charged ions (cations) and negatively charged ions (anions) that are held together by electrostatic forces. The overall stoichiometry of an ionic compound is determined by the requirement that the total positive charge must balance the total negative charge, resulting in a neutral compound. This understanding is crucial when analyzing the composition of the compound to determine the contribution of specific ions.

Molar Mass

Molar mass is the mass of one mole of a substance, calculated by summing the atomic masses of all the atoms present in a molecule or formula unit, as given by the periodic table. In the context of ionic compounds, the molar mass is computed by adding together the masses of the positive and negative ions according to their stoichiometric ratios. This concept is essential when performing percentage composition calculations.

Percentage Composition

Percentage composition refers to the percentage by mass of each element or component in a compound relative to the total molar mass. In the given problem context, it involves determining the mass contribution from the positive ions and expressing it as a percentage of the overall molar mass of the ionic compound. This technique is widely used in chemical analysis and formulation assessments.

Cations

Cations are the positively charged ions in an ionic compound. They contribute to the overall mass of the compound and are crucial in balancing the negative charge of the anions to maintain electrical neutrality. Identifying the mass contribution of the cations enables the calculation of their percentage composition in the ionic substance.

Transcript

00:11 In this question, we're asked to find the percent of the overall molar mass of the compound that's represented by positive ions in this compound.

00:20 So since we know that these are all ionic substances, we can also say that the positive ion is going to be the first element or ion listed.

00:30 So let's go ahead and go through this really quickly.

00:34 So for the first one, we have ammonium chloride.

00:37 Ammonium, we know, is a polyatomic ion, the formula of nh4, a plus 1 charge.

00:46 Chlorine on the other hand is just chlorine and has a negative charge.

00:52 So if we put these two together we can already see that we have a neutral compound.

00:57 So ammonium chloride has this formula here.

01:02 Now to find the percent mass we want to find the overall molar mass.

01:06 So let's go ahead and calculate that as well.

01:09 Nitrogen has a molar mass of 14 grams per mole.

01:14 Hydrogen has a monol mass of 1 gram per mole per atom and chlorine has a molar mass of 1 gram per mole per of 35 .45 grams per mole.

01:27 So for the molar mass, we have 14 plus 1 times 4 plus 35 .45, which equals 53 .45 grams per mole.

01:48 Now, i want to find the percent that's represented by a positive ion, which in this case is ammonium.

01:54 So again, this is 14, and this is 4.

01:57 So the molar mass of the positive is 18 grams per mole.

02:04 Now it's simple.

02:06 We just have to do, let me just move this down a bit.

02:13 We just take 18 grams per mole and divide it by 53 .45 grams per mole times 100 to get our percentage, which comes out to be 33 .67%.

02:41 So let's go ahead and continue this.

02:43 For the next one, we have copper 2 sulfate.

02:47 So we know copper has a plus 2 charge now, and sulfate is a polytomic ion, s .o4, with a minus 2 charge...

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