Calculate the number of moles of the indicated substance...

Key Concepts

Mole Concept

The mole is a fundamental unit in chemistry that quantifies the amount of substance by relating the mass of a substance to the number of atoms, molecules, or ions it contains. It is defined using Avogadro's number, which is approximately 6.022 x 10^23, meaning that one mole of any substance contains that many entities.

Molar Mass

Molar mass is the mass of one mole of a substance expressed in grams per mole (g/mol). It is calculated using the atomic masses of the elements that make up the compound. This mass is crucial for converting a given mass of a substance into moles by using the relationship: moles = mass / molar mass.

Unit Conversions

Unit conversions involve translating between different units of mass (such as milligrams, grams, and kilograms) to ensure consistency in calculations. Converting all values to a common unit, usually grams, is an essential step before applying the mole calculation formula.

Dimensional Analysis

Dimensional analysis is a systematic method used in chemistry to convert one unit to another through the multiplication of conversion factors. It allows the cancellation of units so that the final result is in the desired unit, such as moles, ensuring accuracy in quantitative chemical calculations.

Transcript

00:01 In problem 34, calculate the number of moles of the indicated substance present in each of the following samples.

00:07 So this question is from chapter 8 chemical composition.

00:11 So in the first part, we have given 1 .95 into 10 .5 minus 3 gram of lithium carbonate.

00:21 So the formula of lithium carbonate allayed to co3.

00:24 So the main concept behind this question is that in order to find the number of moles, we simply apply this formula so the number of moles is equal to given mass divide by molar mass so the given mass of the substance divide by the molar mass of that substance or simply number of moles is equal to given mass divide by the molar mass of the substance so the molar mass of lithium carbonate that is 73 .89 so the molar mass mass of allied to co3 is 73 .89 gram per mole.

01:11 So the number of moles we can calculate 1 .95 into 10 to power minus 3 gram divided by 73 .89 gram per mole.

01:24 So on solving we get value 2 .63 into 10 to power minus 5 moles of lithium carbon.

01:33 On it similarly we can apply the same concept in the other parts of the question so in the part b we have given 4 .23 kg of calcium chloride which is cl2 so so this is in kg so the mass given in kg so we can convert into grams so we which we get 4 .23 into 10 is to power 3 gram of calcium chloride so the number of moles is equal to given mass which is 4 .23 into 10 is to power 3 gram divided by the molar mass of calcium chloride so the molar mass of calcium chloride from the product table we can see 110 .98 gram per mole so on solving we get 38 .111 .11 moles of calcium chloride in the third part we have given 1 .0 .9.

02:48 23 milligram of stanchium chloride so the formula of strontium chloride is srcel2 so now this is in milligram so we can convert into gram so we can write 1 .23 into 10 this to power minus 3 gram so apply the formula of number of modes so given mass 1 .23 into 10 this to power minus 3 gram divide by the molar mass of strontium chloride from the product table we get 158 .53 gram per mole.

03:22 Okay so on solving this we get 7 .75 into 10 days to power minus 6 moles of stonium chloride.

03:43 In the party we have given 4 .75 gram of calcium sulfate which is c.

03:55 So four so the number of moles is 4 .75 gram divided by the molar mass of calcium sulfate which is 136 .14 gram per mole so we get 0 .03489 moles of calcium sulfates.

04:25 Now in the part e of the question we have given 96 .2 milligram of nitrogen for oxide.

04:40 Now what it means nitrogen for oxide.

04:42 So it means the formula of of this nitrogen for oxide is no2...

Please give Ace some feedback