What is the formula and name of a hydrate that is 85.3% barium chloride and 14.7% water?

Name: Problem 184, Chapter 10: Chemistry Matter and Change
Uploaded: 2020-05-15T20:39:31-08:00
Duration: 7 min 35 s
Channel: Nicole Powell
Description: What is the formula and name of a hydrate that is 85.3% barium chloride and 14.7% water?

What is the formula and name of a hydrate that is 85.3%...

Key Concepts

Hydrate

A hydrate is a crystalline compound that includes water molecules incorporated into its lattice structure. In these compounds, water is chemically bound in a definite stoichiometric ratio to the other elements, typically represented in the formula by a dot followed by the number of water molecules (e.g., ·nH2O). This concept is fundamental in understanding how water can alter the physical and chemical properties of a compound.

Percent Composition

Percent composition refers to the percentage by mass of each constituent element or component in a compound. This concept is used to analyze the makeup of a compound and is crucial for determining the empirical formula when the percentages of all parts, such as the anhydrous salt and water in a hydrate, are known.

Empirical Formula Determination

Empirical formula determination involves converting the mass percentages of the elements (or components) of a compound into moles and then finding the simplest whole-number ratio of these moles. This process is essential for deducing the chemical formula of a compound, particularly when starting from experimental data such as percentage composition.

Mole Ratio Calculation

Mole ratio calculation is a step in determining the empirical formula where the number of moles of each component, obtained from the percent composition, are divided by the smallest number of moles present. This ratio reveals the relative number of each component in the compound, thereby allowing chemists to infer the exact stoichiometric formula of a hydrate or any other compound.

Transcript

00:01 This question is asking us to find the formula name for a hydrate that is 85 .3 % barium chloride and 14 .7 % water.

00:11 So let's start by finding the formula for each of these.

00:14 For barium chloride, we know there is going to be barium and there's going to be chlorine.

00:22 On its own, barium has a charge of plus two and chlorine has a charge of minus one.

00:30 So in order for this compound to have a total charge of zero, there have to be two chlorine.

00:36 For every barium.

00:39 For water, i hope we all know the formula is h2o, two hydrogens for every oxygen.

00:50 In order to find the formula, we're going to need the ratio of barium chloride to water in terms of moles.

00:58 And so we're going to eventually need to use the molar mass.

01:01 So let's write those down in the hoopla.

01:04 In order to find the molar mass of a compound with multiple atoms, we need to add the molar masses of you of the individual items which can be found on a periodic table.

01:16 So for barium chloride, adding the molar mass of thorium with twice the molar mass of chlorine gives us 208 .28 0 .28 grams per mole.

01:37 And for water, adding twice the lull mass of hydrogen plus the molar mass of oxygen, that gives us 18 .02 grams per mole.

01:54 All right.

01:56 So now we have these percentages that we need to get into grams in order to get moles.

02:03 So we can assume that the hydrate has any number of grams.

02:08 It's easiest to assume 100 grams so that we can keep these numbers as the number of grams for each of the individual compounds within the hydrate.

02:17 So for example, for barium chloride, we have 85 .3 grams.

02:26 And for water we have 14 .7 grams.

02:51 So now that we have grams, we can easily use the molar mass to get the number of moles of each of these.

02:56 So for barium chloride, we can divide by the molar mass, which is the same as multiplying by the reciprocal of the molar mass...

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