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Get Full Access to Virginia Commonwealth University - CHEM 101 - Class Notes - Week 4
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VIRGINIA COMMONWEALTH UNIVERSITY / Chemistry / CHEM 101 / How are grams converted to moles?

# How are grams converted to moles? Description

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★ Converting grams to moles

## How are grams converted to moles?

○ How many moles of PCl3 in 8.0g of PCl3

■ Steps

● 1.)Find the amu (g/mol) by adding all atomic masses

● 1P = 1 x 30.97

3Cl = 3 x 35.45

----------------------

137.32 g/mol

● 2.) do stoichiometry

○ To do that you must start with the given number of grams

in order of grams → moles → moles→ grams

○ 8g PCl3 X 1mole PCl3

----------------------- = 0.058 mol PCl3

137.32g PCl3

★ Converting moles to molecules

○ To do this you must use avogadro's number, 1mol = 6.022 x 10^23 molecules

## How are moles converted to molecules?

★ Determining the amount of atoms present

○ How many Cl atoms are present?

■ To do this you must use the coefficients in the question to solve it started with information given to you and solve using stoichiometry

★ What is a cation and an anion

○ A cation is a element or compound with a positive charge

○ A anion is an element or a compound with a negative charge We also discuss several other topics like What was john locke's role in the declaration of independence?
If you want to learn more check out What are the two principal cell types of the nervous system?

Example

● Al(OH)3

○ Al 3+ → cation

○ OH - → anion

★ Conversions

○ Cm3 = ml

○ Density = mass/volume

○ Use periodic table to convert

Mol←→ g

○ Use avogrados # to convert

Mol ← → #atoms, molecules,ions,ect.

## How can one determine the amount of atoms present in a substance?

○ Examples

G → mol

( periodic table)

★ Limiting reaction

○ Example

■ What is the limiting reactions if you have 75g of N2 and 25g H2

■ N2(G) + 3H2 → N2H3

● 1. Find moles by stoichiometry starting with given measure

● 2. Then divide by coefficient in equation to see which compound

or element will run out first

● 75g N2 x 1 mol’ = 2.678 Moles of N2

---------- ------------------------- = 2.678

28.01gN2 1

25 g H2 X 1 mole = 12.4 moles of H2

------------- ----------------------- = 4.13

2.016g H2 3

Therefor N2 is the limiting factor If you want to learn more check out What is the term for someone who is not transgender, and therefore identifies with their body declared at birth?

★ How much N2H3

○ STEP 1 use given factor and stoichiometry in the order of grams→ mole → moles → grams

○ 75g N2 x 1 mol N2 X 2 mol NH3 X 1.03g NH3

------------ --------------- -------------- = 91.2 If you want to learn more check out What is the objective of merchandising and manufacturing companies?
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28.02g N2 1 mol N2 1 mol NH3

★ What is the theoretical, actual ,and percentage yield of this reaction if the yield of 57? ○ Theoretical is the number you get once finished stoichiometry the yield your supposed to use

○ Actual is the number normally given you because it is the actual yield ○ The percentage yield formula is actual yield/ theoretical yield x 100

■ Theoretical = 91.2

■ Actual = 57

■ Percetal = 57/91.2 X 100 = 62.5%

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