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Spring 2018 > Chem 170 chapter 3 > Flashcards

Chem 170 chapter 3 Flashcards

1
Q

How many atoms of Br are in 35.2g of CH2Br2

A

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

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2
Q

Determine the chemical formula for this experimental data. Se 1.443g Br 5.841g

A

(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

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3
Q

Calculate the mass of sodium in 8.5g of Na3PO4

A 
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

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4
Q

Find moles atoms & grams of an element in a compound

0.0884mol C4H10

A

C: (4) x 0.0884 = 0.3536
H: (10) x 0.0884 = 0.884

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5
Q

Find moles atoms & grams of an element in a compound

2.4+mol C6H12

A

C: (6) x 2.4 = 14.4
H: (12) x 2.4 = 28.8

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6
Q

What is the emperical formula for C10H8

A

C5H4

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7
Q 
Which substance is an ionic compound and why?
SrI2
N2O4
He
CCl4
A

SrI2

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8
Q

What is the correct formula for a compound between calcium and sulfur?

A

CaS

just be sure its balanced 2+ & 2-

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9
Q

Name the compound SrI2

A

Stronlium Iodide

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10
Q

What is the formula for manganese(IV) oxide?

A

MnO2

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11
Q

Name the compound Pb(C2H3O2)2

A

lead(II) acetate

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12
Q

Name the compound P2I4

A

diphosphorus tetraiodide

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13
Q

Name the compound HNO2(aq)

A

nitrous acid

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14
Q

Determine the number of CH2Cl2 molecules in 25g of CH2Cl2

A

1.77 x 10^23 molecules

.294350 X 10^23 = 1.77 x 10^23 molecules

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15
Q

list the elements in the compound CF2Cl2 in order of decreasing mass percent composition

A

Cl > F > C

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16
Q

Determine the mass of potassium in 35.5g of KBr

A

11.7g

  1. 5 / 119.002 (KBRmass) = 0.298314314
  2. 298314314 * 39.098 (K) = 11.66348077
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17
Q

A compound is 52.14% C, 13.13% H, and 34.73% O by mass. What is the empirical formula of the compound?

A

% 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

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18
Q

A compound has the empirical formula CH2O and a formula mass of 120.10 amu. What is the molecular formula of the compound?

A

C4H8O4

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19
Q

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

A

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.

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20
Q

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)

A

1,3,1,3

21
Q

electron gain

A

causes a negative charge (more electrons than protons), these are called anions.

22
Q

electron loss

A

Causes a positively charged atom (fewer electrons than protons) these are called cations.

23
Q

naming

Mg(NO3)2

A

magnesium nitrate

24
Q

Naming Ni2(SO4)3

A

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

25
Q

Naming atom compounds

to name a metal that forms only one type of ion

A

[Name of cation (metal)] + [base name of anion(non-metal) + ide]

ex. CaI2 calcium iodide

26
Q

Naming atom compounds

to name a metal that forms “more” than one type of ion

A

[name of cation(metal)] + [ charge of cation in roman numerals in parenthesis (III) ] + [ base name of anion + ide ]

ex FeCl3 iron(III) chloride

27
Q

Rules for Naming Molecular nonmetals only

A

[ prefix ] + [ name of 1st element ] + [ prefix ] + [ name of 2nd element ]

ex. P2O5 diphosphorus pentoxide

28
Q

Naming Acids rule

Binary Acids w/o oxygen rule

A

[ hydro ] + [ base name of oxyanion + ic] + [ acid ]

ex. HCl hydrochloric acid

29
Q

Naming Acids rule

Binary Acids w/ oxygen rule with 4 oxygen molecules

A

[ base name of oxyanion + ic ] - [ ate] + [ acid ]

ex. H3PO4 phosphoric acid

30
Q

Naming Acids rule

Binary Acids w/ oxygen rule with 3 oxygen molecules

A

[ base name of oxyanion + ic ] - [ ite] + [ acid ]

ex. H2SO3 sulfurous acid

31
Q

Name all the prefixes 1-10

A 
number prefix
1             mono
2            di
3            tri
4            tetra
5            penta
6            hexa
7            sept
8           octa
9           nona
10          deca
32
Q

What is the chemical formula for methane?

A

CH4

33
Q

What is the chemical formula for Permanganate?

A

MnO4

34
Q

Name CuSo4 * 2H2O

A

Copper(II) Sulfate Dihydrate

35
Q

potassium carbontate dihydrate

A

K2CO3 * 2H2O

36
Q

a flask contains .37 moles of liqued Br2. determine the # of bromine molecules present in the flask

A

if the # of molecules is greater than tne # of moles, multiply by avogadros #.

.37 x (6.022x10^23) = 2.23*10^23

37
Q

Calculate the mass of 1.00 X 10^24 molecules of water

A

Get the molar mass of H2O = 18.0138
divide 1.00 X 10^24 by avogadros = 1.66057781

1.66057781 * 18.0138 = 29.91331783

38
Q

Calculate percent composition by mass of C10H22

A

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%

39
Q

A certain metal hydroxide, M(OH)2, contains 32.8 oxygen by mass. What is the identity of the metal M?

A

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)

40
Q

What is the mass of 8.00 × 1022 molecules of NH3?

A

2.26g

41
Q

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.

A

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

42
Q

How many moles of C5H12 contain 9.25 × 1024 molecules of C5H12?

A
  1. 4 moles C5H12

9. 25 × 1024 / avos # = 15.3603454

43
Q

How many moles of N2O4 are in 76.3 g N2O4? The molar mass of N2O4 is 92.02

A

0.829 moles

44
Q

The chemical formula for barium nitride is:

A

Ba3N2

chemical formula means fucking balance the equation

45
Q

Which of the following is a molecular compound?

A

P4O10

46
Q

Determine the empirical formula for a compound that contains C, H and O. It contains 52.14% C and 34.73% O by mass.

A

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

47
Q

Give the structure for lithium hypochlorite.

A

LiClO

48
Q

Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor.

A

2 C2H6(g) + 5 O2(g) → 4 CO(g) + 6 H2O(g)

49
Q

Give the mass percent of carbon in C14H19NO2.

A

72.07%

Spring 2018 (13 decks)

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