Unit 3 Stoichiometry And The Mole

Question 1

Define precision

Answer 1

How close the data is to each other

Question 2

Define Accuracy

Answer 2

How close the data is to the true value

Question 3

What are the three types of errors?

Answer 3

• Random Error
• Gross Error
• Systematic Error

Question 4

What is Avogadro’s Number?

Answer 4

6.022*10^23

Question 5

What is the significance of Avogadro’s Number?

Answer 5

6.022*10^23 is one mole

Question 6

What is the symbol for Avogadro’s Number?

Answer 6

L

Question 7

What is the formula to find moles? and what dose each variable represent?

Answer 7

n = N / L

n is moles
N is number
L Avogadro’s number

Question 8

What are the synonyms for Molar Mass?

Answer 8

Atomic Mass
Molecular Mass
Formula Mass

Question 9

What is the formula for mass - mole conversions? and what do the variables represent?

Answer 9

m = n*MM

m is mass
n is moles
MM is molar mass

Question 10

What are the four types of formula calculations?

Answer 10

1) Determine the empirical formula form the molecular mass
2) Determine the molecular formula given empirical formula and molar mass
3) Determine the percent composition by mass from a formula
4) Determine the empirical formula from percent composition or experimental data

Question 11

What are the states of matter and their symbols?

Answer 11

solid (s)
liquid (l)
gaseous (g)
aqueous (aq)

Question 12

What is the Law of Conservation of Mass?

Answer 12

Matter cannot be created nor destroyed but only changed in form during a chemical reaction

Question 13

What is the volume of one mole of any gas at STP?

Answer 13

22.7 L or 22.7 dm^3

Question 14

What does STP mean and what are the conditions?

Answer 14

Standard Temperature and Pressure
0°C
100 kPa

Question 15

What is the formula to determine percent yield?

Answer 15

percent yield = experimental yield / theoretical yield *100

Question 16

What is the “four step” method?

Answer 16

1) Balance chemical equation
2) Determine the number of moles for the substance whose quantity is given
3) Identify the substance you are required to find the quantity for and determine the mole ratio from the coefficients (ratio is - “given value : required value”)
4) Convert the moles of the required substance into the units needed

Question 17

Define hydrated ion

Answer 17

A metal ion that is chemically bonded to a water molecule

Question 18

Define salt hydrates

Answer 18

salt containing water molecules

Question 19

Define anhydrous salt

Answer 19

A salt hydrate that releases water when heated

Question 20

What are the steps for calculating the empirical formula of hydrates?

Answer 20

1) Determine the mass of water driven out
2) Convert mass of water to moles
3) Determine mass of anhydrous salt
4) Convert mass of anhydrous salt to moles
5) Divide moles of water by moles of anhydrous salt to find whole number ratio

Question 21

Define limiting reactant

Answer 21

The reactant in the reaction that limits the amount of product that forms (will be the reactant that is completely used up)

Question 22

How do you find the limiting reactant?

Answer 22

Use the four step method to find the yields of both reactants and the smaller reactant yield will be your limiting reactant