Chem 1211 Exam 1 Study Guide

law

true 100% of the time

theory

explanation to explain something that happens over and over

accuracy

how close a measurement is to the true value

precision

if repeated measurements show the same result

exact values

values that have no uncertainty; no sigfigs

do leading zeros count as sigfigs?

no

do captive zeros count as sigfigs?

yes

does a zero before the decimal count as sigfig?

no

when do tailing zeros count as sigfigs?

if the number has a decimal

how many sigfigs: 0.0025

2

how many sigfigs: 1502

4

how many sigfigs: 100

1

how many sigfigs: 2306.0

4

how many sigfigs: 1.00 x 10^3\= 3

3

addition/subtraction rule for sigfigs

last digit in common is sig

answer with sigfig notation: 45.9 + 3.2145

49.1

answer with sigfig notation: 1708-4.0

1704

multiplication/division rule for sigfigs

least number of sigfigs is significant

answer with sigfig notation: 45.9 * 2.0

92

answer with sigfig notation: 15.92/19.0

0.838

answer with sigfig notation: (2.4 * 10^3)^2

5.8 * 10^6

answer with sigfig notation: (9.812 * 3.1) +156.4

186

answer with sigfig notation: (283.0-0.099)/4.0100

70.55

answer with sigfig notation: [(6.201)^3 * 0.0451] - 4907

-4896

giga

10^9

mega

10^6

kilo

10^3

hecto

10^2

deka

10^1

deci

10^-1

centi

10^-2

milli

10^-3

micro

10^-6

nano

10^-9

convert 65ft to meters

19.812m

convert 1in to cm

2.54cm

convert 50m to in

1968.5in

convert 158cm to ft

5.18ft

convert 5'5'' to cm

170cm

convert 6.5m to cm

650cm

how many sigfigs: 1.0 x 10^2

2

how many sigfigs: 4.00 x 10^3

3

how many sigfigs: 0.00480

3

how many sigfigs: 4.80 x 10^-3

3

how many sigfigs: 4.800 x 10^-3

4

You have a chemical sealed in a glass container filled with air. The glass container has a mass of 200.0 grams and the chemical has a mass of 800 grams. The total mass of the setup is 1000 grams. The chemical is ignited by means of a magnifying glass focusing sunlight onto the reactant. After the chemical has completely burned, what is the total mass of the setup?

1000g

13C6

protons: 6

neutrons:7

electrons: 6

60Co27 (2+)

protons: 27

neutrons: 33

electrons: 25

18O8 (2-)

protons: 8

neutrons: 10

electrons: 10

97Tc43 (3+)

protons: 43

neutrons: 54

electrons: 40

mixture

non-chemically made

compound

chemically made

The composition of a substance depends on the

number of atoms

Avogadro's hypothesis (law) implies that volume ratios are equal to molecule ratios at constant temperature and pressure. From the balanced equation, H2(g) + Br2(g) → 2 HBrg, (A) molecules of HBr is/are produced per molecule of H2 or Br2 reacted. Therefore, the volume of HBr produced will be (B) times the volume of H2 or Br2 reacted

A\=2

B\=2

law of constant composition

a given compound always contains elements in exactly the same proportion by mass

Saltpeter is a compound made of potassium (K), nitrogen (N), and oxygen (O). Every 100.00 g of saltpeter contains 38.67 g potassium and 13.86 g nitrogen. What is the mass of oxygen contained in 294.0 mg of saltpeter?

0.1396

A sample of chloroform is found to contain 11.8 g of carbon, 104.6 g of chlorine, and 0.99 g of hydrogen. If a second sample of chloroform is found to contain 36.8 g of carbon, what is the total mass of chloroform in the second sample?

366

A colorless, crystalline solid is decomposed, yielding a pale yellow-green gas and a soft, shiny metal.

(A) mixture

(B) compound

(C) chemical change

(D) physical change

B, C

A cup of tea becomes sweeter as sugar is added to it.

(A) mixture

(B) compound

(C) chemical change

(D) physical change

A, D

(1.023e26) x (5.21e-4) answer in SN

5.33e22

if density is given as 491 lb/ft^3, what is it in g/cm^3?

7.87 g/cm^3

h2o boils at 217F. what does it boil at in kelvin?

373k

convert f to c

C\=5/9(F-32)

convert c to k

K\=C+273.15

density

m/v

intensive property

depends on type of matter not amount

extensive property

depends on amount

volume given is 45in^3. what is the volume in mL?

740 mL

what is the mass of a flash of 2.500L ethanol if density is 0.798g/mL and mass of flask is 124.5g?

2120g

find the mass (g) of 5.0x5.0x2.5 (in) piece of al. density\= 2.40g/cm^3.

1in\=2.54cm

2800g

element

one type of atom; distinct \# protons

acronym for diatomic elements

HOFBrINCl

compound

multiple types of atoms with constant compisition

element or compound?

1.Na

2.NaCl

3.Cl2

4.SCl2

1. E

2. C

3. E

4. C

pure substances

only one chemical compound, repetitive