4. Equations

Question 1

Combustion vs combination rxns vs decomposition rxns vs single replacement vs double replacement vs neutralization rxns

Answer 1

hydrocarbon + oxidant (usually O2) -> CO2 + H2O vs A + B -> C vs C -> A + B vs A + BC -> B + AC vs AB + CD -> AD + CB vs subset of double replacement, acid + base -> salt + H2O

Question 2

Steps to balance eqns

Answer 2

Metals/nonmetals, H, O

You balance eqns to reflect laws of mass conservation and charge

Question 3

Know how to find limiting reagent and excess reagent

Answer 3

Convert g to mol, stoich mol of reactant and product; smaller mol value = LR, find difference b/w small and big mol values and change from mol to g

Question 4

Eqn for percent yield. Steps to find it

Answer 4

(actual/theoretical) x 100

1) Balance eqn, 2) use complete stoich to find starting grams given to find target grams, 3) percent yield eqn

Question 5

Is going right or going up more impt for stronger electronegativity?

Answer 5

Right > up

Question 6

[O] #’s for elemental states vs mono atomic ions

Answer 6

0 vs their charge

Question 7

Gram equivalent weight

Answer 7

Molar mass/n
n = # of target particles produced or consumed in a rxn (ex: you need 31 g of H2CO3 (molar mass=62 g) to make 1 equivalent of H ions cuz each H2CO3 gives 2 H ions

Question 8

Normality (N)

Answer 8

Measure of conc expressed in equivalents/L; usually done for [H+]. Ex: 1 N HCl = 1 M HCl cuz there’s 1 H ion, 1 N H2CO3 = 0.5 M H2CO3 cuz there’s 2 H ions
molarity = normality/n where n=# of p+, e-, or ions produced or consumed by solute

Question 9

Law of constant composition. How to find percent composition

Answer 9

Any pure sample of cmpd will have identical mass ratio

(Mass of element in formula/molar mass) * 100

Question 10

Electrolytes and examples

Answer 10

Solutes that allow slns to carry currents. Strong ex: ionic cmpds like NaCl and KI; highly polar covalent bonds that dissociate when dissolved like HCl; ionic cmpds that can dissolve into greatest amount of cat/anions. Weak ex: molec that ionizes or hydrolyzes weakly in water like acetic acid (basically weak acids) and NH3 (basically weak bases)
Electrolytes prevent charge buildup and inc conductivity in electrolysis; electrolytes should not be [O] or [H]

Question 11

Molecular weight vs formula weight

Answer 11

Sum of masses of all atoms within molec vs sum of masses of all atoms within ionic cmpds (usually from empiric formula)

Question 12

How to find empirical formula?

Answer 12

1) imagine percentages in 100 g sample
2) divide percentages by molar mass of element
3) divide the resulting ratio by smaller revalue
4) those answers acts subscripts for empirical formula