chem quiz 3

Question 1

how do you find the empirical formula of a combustiongiven grams of a sample and grams of a product, when only given the elements?

Answer 1

set up an equation AxByCz + CO2 + H2O

Question 2

What is wrong with C3H8(g) +O2(g) -> CO2(g) + H2O

Answer 2

violated conservation of mass, need to balance it

Question 3

what is the Law of conservation of mass

Answer 3

mass is neither created nor destroyed

Question 4

Know how to balance equations

Answer 4

.

Question 5

what do the coefficients tell us in stoichiometry

Answer 5

the ratio of compounds needed to produce also moles

Question 6

How do you figure out how much hydrogen you need and how much ammonia you can make given moles of nitrogen

Answer 6

1.8molN2 x 3mol H/1mol N2 = 5.4 mol H
1.8molN2x 2NH3/ 1molN2 = 3.6 mol NH3
you use the ratios that you know from the formula of NH3 and just multiply given mols by the moles of each substance in the ratio

Question 7

how do you figure out how much CO2 is produced in g given grams of a polyatomic

Answer 7

set up a balanced combustion reaction
use that to determine ratios
multiply given grams of poly by 1 mol of poly/molar mass poly by ratio of C2/poly by mol mass CO2/ 1 mol CO2

Question 8

what is theoretical yield

Answer 8

product

Question 9

% yield formula

Answer 9

actual yield/ theoretical yield x 100%

Question 10

what is actual yield

Answer 10

how much you actually get

Question 11

what is theoretical yield

Answer 11

expected to make based on limited reactant

Question 12

how do you determine theoretical yield given grams of each reactant

Answer 12

multiply grams of first element in equation by mol of 1st element/molarmass by mol product/mol 1st element (all should be done in ratios of balanced equation)

Question 13

how to figure out actual yield given known percent yield

Answer 13

divide given percent by 100 and multiply it by theoretical yield

Question 14

what is a solvent

Answer 14

the thing that does the dissolving

Question 15

what is solute

Answer 15

the thing being dissolved

Question 16

what is a solution

Answer 16

a mixture of 2 or more things

Question 17

what happens when an ionic compound is dissolved

Answer 17

it dissociates

Question 18

soluble compounds

Answer 18

alkali metal, (Li, Na, K, Rb, Cs), ammonium ion (NH4)), Nitrates (NO3), acetates (CH3COO), bicarbonates (HCO3), chlorates (ClO3) perchlorates (ClO4), halides (Cl, Br, I) usually, sulfates (SO4^2-)

Question 19

what are the soluble compound exceptions

Answer 19

Halides Cl,Br,I paired with AG, Hg2, Pb^2+

Question 20

insoluble compounds

Answer 20

Carbonates (CO3 ^2-), phosphates (Po4^3-), chromates (CrO4^2-), sulfides (s^2-)
Hydroxides (OH-)

Question 21

insoluble compound exceptions

Answer 21

compounds containing alkali metals and ammonium ions; compounds containing alkali metals and the Ba^2+ ions

Question 22

how do you answer: what happens if you add ___ to water

Answer 22

make equations ex: KI(s) + H2O(l) -> KI(aq)+ H2O (l)

change s to aq if it dissolves

Question 23

predict the precipitate

Answer 23

pair the first element with the last and the remaining together (double replacement reaction) cross charges and predicte state of matter in ()

Question 24

net ionic eqn

Answer 24

separate each compound and write + (aq) if it is aqueous

ex: NH4Cl(aq) becomes NH4 + (aq) + Cl +Aq)