Chem 170 chapter 3 Flashcards
How many atoms of Br are in 35.2g of CH2Br2
ANSWER: 2.44x10^23 amu Br
How?
add element masses together of CH2Br2 = 174.0 g/mol
35.2g x (1mol/174gmol) = 0.202
Br(2) x (0.202) = 0.404
(0.404) x (6.022x10^23”avagadros” / 1mol) = 2.44x10^23 amu Br
Determine the chemical formula for this experimental data. Se 1.443g Br 5.841g
(Se 1.443g) / (Se = 78.96g/mol) = 0.018
(Br 5.841g) / (Br = 79.9g/mol) = 0.073
divide by the smallest #
(0.073) / (0.018) = 4.055
Answer = Se1Br4
Calculate the mass of sodium in 8.5g of Na3PO4
Na = 22.990 x (3) = 68.97 P = 30.974 x (1) = 30.974 O = 15.998 x (4) = 63.992 Total = 163.936
8.5 x (1mol / 163.936) = 0.05 mole
Na3PO4 = 0.05 Na : (3) x 0.05 = 0.15
0.15 x (23 / 1moll) = 3.45
Find moles atoms & grams of an element in a compound
0.0884mol C4H10
C: (4) x 0.0884 = 0.3536
H: (10) x 0.0884 = 0.884
Find moles atoms & grams of an element in a compound
2.4+mol C6H12
C: (6) x 2.4 = 14.4
H: (12) x 2.4 = 28.8
What is the emperical formula for C10H8
C5H4
Which substance is an ionic compound and why? SrI2 N2O4 He CCl4
SrI2
What is the correct formula for a compound between calcium and sulfur?
CaS
just be sure its balanced 2+ & 2-
Name the compound SrI2
Stronlium Iodide
What is the formula for manganese(IV) oxide?
MnO2
Name the compound Pb(C2H3O2)2
lead(II) acetate
Name the compound P2I4
diphosphorus tetraiodide
Name the compound HNO2(aq)
nitrous acid
Determine the number of CH2Cl2 molecules in 25g of CH2Cl2
1.77 x 10^23 molecules
.294350 X 10^23 = 1.77 x 10^23 molecules
list the elements in the compound CF2Cl2 in order of decreasing mass percent composition
Cl > F > C
Determine the mass of potassium in 35.5g of KBr
11.7g
- 5 / 119.002 (KBRmass) = 0.298314314
- 298314314 * 39.098 (K) = 11.66348077
A compound is 52.14% C, 13.13% H, and 34.73% O by mass. What is the empirical formula of the compound?
% H = 100 - ( 52.14 + 34.73 )=13.13 %
assume 100 g of this compound
mass H = 13.13 g
moles H = 13.13 g / 1.008 g/mol=13
mass C = 52.14 g
moles C = 52.14 g/ / 12.011 g/mol=4
mass O = 34.73 g
moles O = 34.73 g/ 15.999 g/mol=2
the empirical formula is C4H13O2
A compound has the empirical formula CH2O and a formula mass of 120.10 amu. What is the molecular formula of the compound?
C4H8O4
Combustion of 30.42g of a compound containing only carbon, hydrogen, and oxygen produces 35.21 g of CO2 and 14.42 g of H2O. What is the empirical formula of the compound?
a) C6HO12 b) C2H2O3 c) C2H4O3 d) C4H8O6 e) CHO
C2H4O3
Combustion analysis yields information about compound C and H content only, so we can determine the mole ratio of C:H in the compound by the following: (35.21 g CO 2 )(1 mol CO 2 / 44 g)(1 mol C / mol CO 2 ) = 0.8 mol
C (14.42 g H 2 O)(1 mol H 2 O / 18 g)(2 mol H / 1 mol H 2 O) = 1.6 mol
H 0.8 mol C : 1.6 mol H :: 1 mol C : 2 mol H
Thus, the empirical formula must be a lowest whole number formula giving a 1:2 mole ratio for C:H, which only answer (c) does. Answer (c) is correct.
What are the correct Coefficients of the formula (reading from left to right) when the chemical equation is balanced?
_PCl3(l) + _H2O(l) -> _H3PO3(aq) + _HCl(aq)
1,3,1,3
electron gain
causes a negative charge (more electrons than protons), these are called anions.
electron loss
Causes a positively charged atom (fewer electrons than protons) these are called cations.
naming
Mg(NO3)2
magnesium nitrate
Naming Ni2(SO4)3
Nickel(III) Sulfate
cation must equal positive charge must equal anion negative charge
(SO4) has a charge of -2 * 3 = 6
Nickel must be multipied by 2, what multiplied by 2 = 6?
3 * 2 = 6
Naming atom compounds
to name a metal that forms only one type of ion
[Name of cation (metal)] + [base name of anion(non-metal) + ide]
ex. CaI2 calcium iodide
Naming atom compounds
to name a metal that forms “more” than one type of ion
[name of cation(metal)] + [ charge of cation in roman numerals in parenthesis (III) ] + [ base name of anion + ide ]
ex FeCl3 iron(III) chloride
Rules for Naming Molecular nonmetals only
[ prefix ] + [ name of 1st element ] + [ prefix ] + [ name of 2nd element ]
ex. P2O5 diphosphorus pentoxide
Naming Acids rule
Binary Acids w/o oxygen rule
[ hydro ] + [ base name of oxyanion + ic] + [ acid ]
ex. HCl hydrochloric acid
Naming Acids rule
Binary Acids w/ oxygen rule with 4 oxygen molecules
[ base name of oxyanion + ic ] - [ ate] + [ acid ]
ex. H3PO4 phosphoric acid
Naming Acids rule
Binary Acids w/ oxygen rule with 3 oxygen molecules
[ base name of oxyanion + ic ] - [ ite] + [ acid ]
ex. H2SO3 sulfurous acid
Name all the prefixes 1-10
number prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 sept 8 octa 9 nona 10 deca
What is the chemical formula for methane?
CH4
What is the chemical formula for Permanganate?
MnO4
Name CuSo4 * 2H2O
Copper(II) Sulfate Dihydrate
potassium carbontate dihydrate
K2CO3 * 2H2O
a flask contains .37 moles of liqued Br2. determine the # of bromine molecules present in the flask
if the # of molecules is greater than tne # of moles, multiply by avogadros #.
.37 x (6.022x10^23) = 2.23*10^23
Calculate the mass of 1.00 X 10^24 molecules of water
Get the molar mass of H2O = 18.0138
divide 1.00 X 10^24 by avogadros = 1.66057781
1.66057781 * 18.0138 = 29.91331783
Calculate percent composition by mass of C10H22
C(10) x 12.011 = 120.11
H(22) x 1.0079 = 22.1738
total = 142.2838
(120. 11) / 142.2838 = 84.41%
(22. 1738) / 142.2838 = 15.58%
A certain metal hydroxide, M(OH)2, contains 32.8 oxygen by mass. What is the identity of the metal M?
mass O in 100 g = 32.8 g
moles O in 100 g = mass / molar mass = 32.8 g / 16.00 g/mol = 2.05 moles
The formula is M(OH)2
So for every 1 mole O there is 1 mole H
So moles H in 100 g = 2.05 moles
mass H = molar mass x moles
= 1.008 g/mol x 2.05 moles
= 2.0664 g H in the 100 g
mass M in 100 g = total mass - mass H - mass O
= 100 g - 2.0664 g - 32.8 g
= 65.1336 g of metal M
We also know that for each moles O there is 1/2 mole M (M(OH)2)
So moles M = 1/2 x 2.05 mol
= 1.025 moles
So 1.025 moles of metal M has a mass of 65.1336 g
molar mass = mass / moles
molar mass = 65.1336 g / 1.025 moles
= 63.5 g/mol (3 sig figs)
look up on periodic table
metal with molar mass 63.5 g/mol = copper (Cu)
What is the mass of 8.00 × 1022 molecules of NH3?
2.26g
How many atoms of oxygen are contained in 47.6 g of Al2(CO3)3? The molar mass of Al2(CO3)3 is 233.99 g/mol.
1.10 × 1024 O atoms
47.6/233.99 = .20342
.20342 x 9((CO3)3 = 9) = 1.830847
1.830847 x avo = 1.102536x10^24
How many moles of C5H12 contain 9.25 × 1024 molecules of C5H12?
- 4 moles C5H12
9. 25 × 1024 / avos # = 15.3603454
How many moles of N2O4 are in 76.3 g N2O4? The molar mass of N2O4 is 92.02
0.829 moles
The chemical formula for barium nitride is:
Ba3N2
chemical formula means fucking balance the equation
Which of the following is a molecular compound?
P4O10
Determine the empirical formula for a compound that contains C, H and O. It contains 52.14% C and 34.73% O by mass.
C2H6O
get Hydrogen % 100-52.14-34.73= 13.13 H C 52.14 / 12.011 = 4.33 H 13.13 / 1.0078 = 13 O 34.73 / 15.999 = 2.2
Get the lowest #
2.2
4.33/2.2 = 2
13 / 2 = 6
2.2 / 2.2 = 1
Give the structure for lithium hypochlorite.
LiClO
Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor.
2 C2H6(g) + 5 O2(g) → 4 CO(g) + 6 H2O(g)
Give the mass percent of carbon in C14H19NO2.
72.07%
