Unit 5: Chemical Reactions

Question 1

what is a hydrocarbon

Answer 1

• compound composed of hydrogen and carbon
• may contain other elements, like oxygen

Question 2

what is hydrocarbon combustion

Answer 2

when a hydrocarbon is burned in oxygen and produces water and carbon dioxide

Question 3

general equation for hydrocarbon combustion

Answer 3

hydrocarbon + oxygen(O2) —> carbon dioxide(CO2) + water(H2O)

Question 4

what are stoichiometric coefficients

Answer 4

• the number in front of compounds in a chemical equation
• show how many moles of each compound is needed

Question 5

what must chemical equation be

Answer 5

• balanced
• same number of atoms of each element on the reactant and product sides

Question 6

how would you determine how many grams of a product are created from a specified number of grams of a reactant

Answer 6

• reaction stoichiometry
• grams of reactant to moles of reactant to moles of product to grams of product

Question 7

how do you know the molar conversions between compounds in reaction stoichiometry

Answer 7

• stoichiometric coefficients
• X moles of one compound makes Y moles of another

Question 8

what do alkali metals produce when reacting with water

Answer 8

hydrogen gas (H2)

Question 9

define limiting reagent

Answer 9

reactant that is the first to be completely consumed in a reaction

Question 10

define excess reagent

Answer 10

any reactant that remains once the limiting reagent has been completely consumed

Question 11

describe the process of determining the limiting reagent

Answer 11

• determine the limiting reagent by comparing moles of one reagent to moles of another reagent
• convert each reagent from grams to moles
• divide by stoichiometric coefficient
• smallest number is limiting reagent

Question 12

when determining how much of a product is formed, should you use the limiting or excess reagent

Answer 12

limiting

Question 13

how do you determine how much of the excess reactant is left over

Answer 13

g initial excess reactant - g limiting reactant that actually reacted = g excess reactant

Question 14

what is the equation for percent yield

Answer 14

actual yield/theoretical yield x 100

Question 15

define theoretical yield

Answer 15

maximum calculated obtainable yield

Question 16

define actual yield

Answer 16

the amount of product obtained from a reaction