Chemistry Semester 1 Final Prepartion

_ is the study of matter and the changes it undergoes.

Chemistry

_ is a measure that reflects the amount of matter in a given sample. It differs from _, which takes into account not only the amount of matter present, but also the Earth’s gravitational pull on matter.

Mass, weight

Examples of SI base units

second, meter, kilogram

Which value is NOT equivalent to the others? a) 5×10^11 nm b) 500 m c) 5000 cm d) 0.5 km

5000 cm

What is 702.0 g in scientific notation?

7.020×10²

How many significant figures are there in 20.070 km?

5

The directions in a candy recipe instruct the cook to remove the pot containing the candy mixture from heat when it reaches a temperature of 236 degrees F. Can a Celsius thermometer with a range of -10 degrees C to 110 degrees C be used to determine when to remove the mixture from heat?

No, the Celcius thermometer cannot be used because 236 degrees F = 113 degrees C and 113 degrees C > 110 degrees C

Conversion between Celcius and Fahrenheit

F = 1.8(C) + 32

If each X represents a significant figure, write XXX.XX in scientific notation.

X.XXXX * 10²

If each X represents a significant figure, write 0.000000XXX in scientific notation.

X.XX * 10^-7

Percent error =

absolute value of error / accepted value * 100

Density formula

D = m/v

Calculate the density of the sample. If the accepted density of this sample is 6.95 g/mL, calculate the percent error. Mass = 20.46 g. Volume of water = 40.0 mL. Volume of water + sample = 43.0 mL

Density = 6.82 g/mL. % error = 1.87%

Evaluate the following conversion. Will the answer be correct? rate = 75m/s * 60s/min * 1h/60min

It is incorrect because the conversion factor for min. to hr. reads as hr. to min. It should say * 60 min / 1 hr.

(6.23 × 10^6 kL) + (5.34 × 10^6 kL)

1.157 × 10^7 kL

(4.68 × 10^-5 cg) + (3.5 × 10^6 kL)

5.03 × 10^-5 cg

(3.57 × 10² mL) - (1.43 × 10² mL)

2.14 × 10² mL

(9.87 × 10^4 g) - (6.2 × 10³ g)

9.25 × 10^4 g

A troy ounce is equal to 480 grains, and 1 grain is equal to 64.8 milligrams. If the price of gold is $560 per troy ounce, what is the cost of 1 g of gold?

$18.00

When multiplying 602.4 m by 3.72 m, which value determines the number of significant figures in the answer? Explain.

Since 3.72 has the least amount of sig figures, it should be used. So there should be 3 sig figures in the answer.

Round to the correct number of significant figures. (7.31×10^4) + (3.23 × 10³)

10.5 × 10^4

(8.54 × 10^-3) - (3.41 × 10 ^-4)

8.20 × 10^-3

4.35 dm * 2.34 dm * 7.35 dm

74.8 dm³

4.78 cm + 3.218 cm + 5.82 cm

13.82 cm

38,736 km / 4,784 km

8.097 km

How can you find the slope of a line graph?

m = y2 - y1 / x2 - x1

3.01 g to cg

301 cg

6200 m to km

6.200 km

0.13 cal/g to kcal/g

0.00013 kcal/g

What mass of lead (density 11.4 g/cm³) would have a volume identical to 15.0 g of mercury (density 13.6 g/cm³)

m = 12.5 grams

Three students use a meterstick with millimeter marking to measure a length of wire. Their measurements are 3 cm, 3.3 cm, and 2.87 cm, respectively. Explain which answer was recorded correctly.

The final one, 2.87cm was calculated correctly. Since the meterstick had millimeter markings, the students should have had 2 known digits and 1 estimated digit. The last measurement fits those requirements.

(4.8 × 10⁵ km) * (2.0 × 10³ km)

9.6×10^8 km²

(3.33 × 10^-4 m) * (3.00 × 10^-5 m)

9.99×10^-9 m²

(8.42 × 10⁸ kL) / (4.21 × 10³ kL)

2.00×10^5kL

(8.4 × 10⁶ L) / (2.4 × 10^-3 L)

3.5×10^9L

When subtracting 61.45 g from 242.6 g, which value determines the number of significant figures in the answer?

The value that determines the number of significant figures the answer is 242.6g because it has the least amount of significant figures. And in subtraction the result should be rounded to the same number of decimal places as the value with the least amount of decimal places.

Atoms with the same number of protons but different numbers of neutrons

isotope

The smallest particle of an element that retains the properties of that element

atom

The weighted average mass of an element’s isotopes

atomic mass

The center-most part of an atom where the protons and neutrons are contained

nucleus

Equal to 1/12 the mass of a carbon-12 atom

atomic mass unit

Ray of radiation traveling from the cathode to the anode

cathode ray

States that all matter is composed of atoms

Dalton’s atomic theory

Compare and contrast the terms mass number and atomic number.

The mass number is the number of protons and neutrons in an atom. The atomic number is only the number of protons. Both are useful when classifying atoms.

Use a periodic table. Which element has the atmoic number 65.

Terbium

Use a periodic table. Which element has 78 protons.

Platinum

Use a periodic table. Which element has 44 protons and 44 electrons?

Ruthenium

Use a periodic table. Which element has an atomic number of 24?

Chromium

Use a periodic table. Which element has 21 protons?

Scandium

Use a periodic table. Which element has an atomic number of 55?

Cesium

True or false? An atom’s nucleus contains its protons and electrons.

False

True or false? Neutrons have no electrical charge.

True

Write neon-22 in symbolic notation.

22 10 Ne

Write cessium-133 in symbolic notation.

133 55 Cs

Write helium-4 in symbolic notation.

4 2 He

Write uranium-234 in symbolic notation.

234 92 U

Describe Thompson’s plum pudding atomic model.

In Thompson’s plum pudding model, the electrons were all mixed inside the atom.

Describe Rutherford’s nuclear atomic model.

In Rutherford’s nuclear model, the electrons were on the outer edges of the atom, orbiting a positively charged nucleus.

How are Thompson’s plum pudding atomic model and Rutherford’s nuclear atomic model similar?

In both models, negatively charged electrons were present in the atoms and both models sought to explain the composition of the atom.

What is the symbol, the location, and the relative charge of a proton?

p, in the nucleus, +1

What is the symbol, the location, the relative charge, and the relative mass of a neutron?

n, in the nucleus, 0, 1

What is the symbol, the location, and the relative charge of an electron?

e^-, surrounding the nucleus, -1

Antimony (Sb) has two stable isotopes. 121Sb has a mass of 120.90 amu. 123Sb has a mass of 122.90 amu. Write an equation to describe the relationship between the percent abundance of 121 Sb and the percent abundance of 123 Sb. Assume no other isotopes exist.

(120.90 * % abundance)+(122.90 * % abundance)=121.760

% abundance of 121Sb + % abundance of 123Sb=100%

you would need a system of equations

Write an equation that you can use to calculate the percent abudnace of each isotope.

(mass of isotope 1 × percent abundance of isotope 1) + (mass of isotope 2 × percent abundance of isotope 2) = atomic mass

% abundance of isotope 1 + % abundance of isotope 2 = 1

What is antimony’s atomic mass? Use the periodic table.

121.760

Calculate the percent abundance for each isotope of antimony.

121Sb = 57%

123Sb = 43%

Which of the isotopes listed are the same element? Explain your reasoning.

Isotope	Number of Protons
Isotope 1	24
Isotope 2	24
Isotope 3	26
Isotope 4	24
Isotope 5	24
Isotope 6	26

Isotopes 1, 2, 4, and 5 are all Chromium. Isotopes 3 and 6 are iron. When isotopes have the same number of protons, they are the same element.

Explain why the mass of each isotope is not a whole number.

Isotope	Number of Protons	Mass
Isotope 1	24	49.946
Isotope 2	24	51.941
Isotope 3	26	55.999
Isotope 4	24	52.941
Isotope 5	24	53.939
Isotope 6	26	56.969

The mass of each isotope isn’t a whole number because protons and neutrons are not exactly 1 amu.

Assume that Isotope 1 is an isotope of element X and that all the isotopes of X are listed in the data table. Determine the atomic mass of X.

Isotope	Number of Protons	Mass	Percent Abundance
Isotope 1	24	49.946	4.35
Isotope 2	24	51.941	83.80
Isotope 3	26	55.999	81.32
Isotope 4	24	52.941	9.5
Isotope 5	24	53.939	2.35
Isotope 6	26	56.969	18.68

51.996

If a chemist later discovered the an Isotope 7 with 24 protons, 24 electrons, 31 neutrons, and a mass of 51.939, what could you conclude?

Isotope	Number of Protons	Mass	Percent Abundance
Isotope 1	24	49.946	4.35
Isotope 2	24	51.941	83.80
Isotope 3	26	55.999	81.32
Isotope 4	24	52.941	9.5
Isotope 5	24	53.939	2.35
Isotope 6	26	56.969	18.68

I could conclude that the revised atomic mass number would decrease slightly because 51.939 is smaller than the original mass number of 51.996 so isotope 7 would bring down the average.

a homogeneous mixture

solution

law that states that mass is neither created nor destroyed in a chemical reaction

conservation of mass

law that states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass

definite proportions

law that states that different masses of one element combine with the same relative mass of another element to form different compounds

multiple proportions

the grid organizing elements into periods and groups

periodic table

the ratio of the mass of each element to the total mass of the compound

percent by mass

three physical forms that describe the matter that exists on Earth

states of matter

a separation technique that results in the formation of pure solid particles from a solution

crystallization

a technique that separates the components of a mixture

chromatography

a form of matter with a constant volume that takes the shape of its container

liquid

a form of matter with a definite shape and volume

solid

chemical property

A chemical property refers to chemical makeup and chemical reactivity.

physical property

A physical property refers to a physical characteristic such as density or boiling point.

How are physical and chemical properties similar.

Both are types of properties that refer to matter.

substance

A substance is either an element or compound.

mixture

A mixture is a combination of 2+ substances which retain the characteristics of each.

How are substances and mixtures similar?

They are both terms that describe matter.

What sort of property is the chemical formula CO

chemical

What sort of property is “forms green carbonate when exposed to air”

chemical

What sort of property is “does not react with nitrogen”

chemical

What sort of property is “colorless”

intensive physical

What sort of property is “solid at room temperature”

intensive physical

What sort of property is “ability to combine with another substance”

chemical

What sort of property is the melting point?

intensive physical

What sort of property is mass?

extensive physical

What sort of property is “conducts electricity”

intensive physical

What sort of property is density

intensive physical

Is phosphorus an element?

yes

Is sodium chloride an element?

no

Is francium an element?

yes