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Stoichiometry (IB Chem Chapter 1) Cheat Sheet (DRAFT) by

Guide to Chapters 1.1, 1.2 and 1.3 in IB Chem DP1 Includes: Finding moles, volume and concentration Limiting and excess reagents Titrations and STandard solutions Ideal Gas Law

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Formulas

No. of molecules = n [no. of moles] x A [Avoga­dro's Constant]
No. of moles (n) = Mass (m)/ Molar Mass (Mr)
No. of Atoms = No. of Molecules [n x A] x Atomicity
No. of moles (n) = Volume (dm3) / Molar volume (STP or RTP)
% yield = [Exper­imental yield/ Theore­tical Yield] x 100
C [molarity] = no. of moles [n]/ Volume of concen­tration [v]
Ideal Gas Law - PV = nRT
Volume­/co­nce­ntr­ation constant - C1V1 = C2V2

Finding Percentage Yield of a Reaction

Note: % yield always applies on PRODUCTS
1: In any situation, first determine which of the products is the limiting reagent
2: Using the compound which is limiting, form a ration such that [limiting reactant : product]
3: Under the ratio, write the coeffi­cient ratio of reactant : product
4: Add the molar mass OF 1 MOLE
5: Multiply the Molar mass with the number of moles = mass value
6: Cross multiply to find the THEORE­TICAL YIELD
7: Use the mass of the product given in the question - (EXPER­IMENTAL YIELD)
8: Substitute in the formula: [Exper­imental Yield/ Theore­tical Yield] x 100 to find % yield
 

How to Find the Limiting Reagent

Step 1: Write down the whole equation
Step 2: Balance the entire equation
Step 3: Using the balanced equation, determine the coeffi­cient ratio of the reactants
Step 4: Write down the ratios of the values given in the question
Step 5: Convert the amounts to moles
Step 6: divide the values (mole ratio / coeffi­cient ratio)
Ans: The smallest value is the limiting reagent

Ideal Gas Law

PV = nRT; where
P - Pressure (Pa)
V = Volume (m3)
T - Temper­ature (K) *Take celsius value and + 273
R - Constant (8.31 JK/mol)
n - no. of moles (mol)
 

Molar Volume Values

STP - Standard Temper­ature and Pressure
RTP - Room Temper­ature and Pressure
Temp.: 0 degrees Celsius
Temp.: 20 degrees Celsius
Pressure: 1 atm
Pressure = approx. 1atm
Volume: 22.7 dm3
Volume: 24 dm3

Ideal Gas vs. Real Gas

Ideal Gas
Real Gas
Obeys all gas laws
All properties change
No forces of attraction
Forces of attraction
Collide in straight lines
Collision in random motion
No mass or volume
High Temper­ature
Low Temper­ature
Low Pressure
High Pressure
High Volume
Low Volume

Steps to Find a Standard Solution

Standard Solution: a solution of accurately known concen­tration
Step 1: Weigh a known amount of solute
Step 2: Dissolve the Solute in a minimal amount of water
Step 3: Transfer the solution to a volumetric flask without washing
Step 4: Make the solution fill the flask till the meniscus reaches accurate value
Step 5: Place stopper and invert into mix solution