Exam 1 Homewok
Add the following numbers. Report answers in correct units, the correct number of decimal points, and follow the correct rounding rules. 0.0853 ps + 0.0547 ps + 0.0370 ps + 0.00387 ps =
0.1809 ps
250.0 grams of a white powder takes up 391.69 cm3. What is the density of the solid substance?
0.6
Determine the number of significant digits in the following measurement 2 x 1018 m
1
Express the following number in scientific exponential notation with correct significant figures. 1000
1 x 10^3
One US gallon equals 3.785 L. What is the mass in grams of 0.294 US gallon of water at room temperature, assuming a density of 1.000 g/mL?
1,113
The density of water at room temperature is 1.005/mL. What is the mass of 1.146 L of water in grams?
1,152
What is the difference between an atom and a molecule?
1. Atom is the smallest particle of an element. Molecule is made of two or more atoms. 2. Atom cannot be separated into subatomic particles by chemical reactions. Molecule can be separated into atoms by chemical reactions.
Express the following number in scientific exponential notation with correct significant figures. 1005.00
1.00500 x 10^3
A molecule of antifreeze, ethylene glycol, has the formula C2H4(OH)2. How many atoms are there in one molecule of antifreeze?
10
Bromine is a reddish-brown liquid with a density of 3.10 g/mL. What is the volume of 31.1 g of bromine?
10
One liter is equal to
1000 mL
Add the following numbers. Report answers in correct units, the correct number of decimal points, and follow the correct rounding rules. 16.5 m + 80 m + 4.37 m =
101 m
The prefix "micro" (u) for numerical units refers to
10^-6
Subtract the following numbers. Report answers in correct units, the correct number of decimal points, and follow the correct rounding rules. 23.27 dl - 12.058 dl =
11.21 dl
Density is defined as the Mass (weight) of a substance divided by its Volume, or D = M / V. Calculate the Volume of 150 grams of a substance that has a Density of 1.20 grams/mL.
125 mL
An atom of the isotope chlorine-37 consists of how many protons, neutrons, and electrons? (p = proton, n = neutron, e = electron)
17 p, 20 n, 17 e
A person is 6.00 ft tall. Convert this height into centimeters. Use the following conversion factors: 1.00 inches = 2.54 centimeters 1 foot = 12 inches Use correct significant numbers
183
Determine the number of significant digits in the following measurement 0.0067 s
2
Determine the number of significant digits in the following measurement 0.070 mL
2
How many nitrate ions react with a barium ion to form barium nitrate?
2 Barium nitrate: Ba(NO3)2
The ionic charge of an oxygen ion is
2-
Multiply the following numbers. Report answers in the correct number of significant digits. 628 x 342 =
215,000 2.15 x 10^5
What is the volume of 322 g of a solution that has a density of 1.32 g/mL?
244
If it takes you 26 gallons of gas to drive 650 miles, what gas mileage in miles/gal is this?
25
Divide the following numbers. Report answers in correct units and in the correct number of significant digits. 445.0𝑔/0.15𝑐𝑚3=
2967 g/cm^3 3000 g/cm^3 3.0 x 10^3 g/cm^3
Determine the number of significant digits in the following measurement 30.07 g
4
Multiply the following numbers. Report answers in the correct number of significant digits and the correct exponential format. (5.63 x 102) x (7.4 x 103) =
4.2 x 10^6
Determine the number of significant digits in the following measurement 270.00 km
5
Express the following number in scientific exponential notation with correct significant figures. 547.9
5.479 x 10^2
The mass sample is 55 milligrams. Which of the following expresses that mass in grams?
5.5 * 10^-2 g
Divide the following numbers. Report answers in correct units and in the correct number of significant digits. 35𝑔/0.62𝑠=
56 g/s
Express the following number in scientific exponential notation with correct significant figures. 711.0
7.110 x 10^2
Subtract the following numbers. Report answers in correct units, the correct number of decimal points, and follow the correct rounding rules. 13.57 cm - 6.3 cm =
7.3 m
Express the following number in scientific exponential notation with correct significant figures. 90743
9.0473 x 10^4
Multiply the following numbers. Report answers in correct units and in the correct number of significant digits. 3.78 m x 2.6 m =
9.8 m^2
What is the difference between a chemical and a physical change?
A chemical change is a matter converted from one type to another type. A physical change is a phase of a substance that changes between solid, liquid, and gas states.
What does the chemical formula represent?
A molecular formula uses chemical symbols to show the types and number of atoms in a compound or molecule. A structural formula shows the type and number of atoms in a compound, but also how the atoms relate to each other. An empirical formula shows the simplest whole-number ratio of the atoms in a substance.
chlorine and aluminum
AlCl3
What is the difference between an element and a compound?
An element is a pure substance that cannot be broken down into simpler substances by chemical means. A compound is a pure substance composed of atoms of two or more elements chemically bonded in fixed proportions.
What is an atom?
Atom is the smallest particle of an element that has the specific properties of that element.
Iodine and Calcium
CaI2
Ion with +1 charge, atomic number 55 and mass number 133
Cesium. Cs^1+
Does the following statement describe a physical change or a chemical change? The iron in discarded automobiles slowly forms a reddish-brown crumbly crust.
Chemical change
Does the following statement describe a physical change or a chemical change? Yellow-green chlorine gas attacks silvery sodium metal to form white crystals of sodium chloride.
Chemical change
Which elements is a gas at room temperature
Chlorine
sulfur and cesium
Cs2S
A gas has a fixed volume and a fixed shape.
False
A solid has a fixed volume but not a fixed shape.
False
When an alkali metal combines with a non-metal, a molecular compound is formed.
False
Ferric oxide is used as a pigment in metal polishing. Which of the following is its formula? FeO Fe2O FeO3 Fe2O5 Fe2O3
Fe2O3
Ion with 54 electrons, 53 protons and 74 neutrons
Iodide. I^1-
Why do all the atoms of an element have the same atomic number, but may have different mass numbers? What is that form called?
Isotopes are atoms of the same element that have different numbers of neutrons but the same number of protons and electrons.
magnesium and nitrogen
Mg3N2
Ion with mass number 14 and -3 charge
Nitride. N^3-
Which of the following is the correct chemical formula for molecular oxygen?
O2
Which of the following compounds is molecular? CaCl2 MgO Al2O3 Cs2S PCl3
PCl3
The correct name for H3PO4
Phosphoric acid
Does the following statement describe a physical change or a chemical change? A magnet separates a mixture of black iron shavings and white sand.
Physical change
Does the following statement describe a physical change or a chemical change? Sodium chloride is heated until it melts.
Physical change
Does the following statement describe a physical change or a chemical change? The volume of a sample of oxygen gas changes from 10 mL to 15 mL as the temperature changes.
Physical change
The atomic nucleus has a positive charge due to the number of
Protons
What is the difference between a proton and an electron?
Protons have a positive charge. -Electrons have a negative charge.
What is the difference between a neutron and a proton?
Protons have a positive electrical charge, but neutrons have no charge.
What is the difference between a pure substance and a mixture?
Pure substances have constant composition are made up of only one kind of particles and can only be broken down by chemical means. A mixture is a combination of two or more substances in varying amounts and in which the substances retain their identities.
What are the different states of matter?
Solid, Liquid, and Gas.
strontium and fluorine
SrF2
Ion with mass number 32, -2 charge and 16 neutrons
Sulfide. S^2-
What are the particles that make up an atom?
The atomic nucleus consists of protons and neutrons. Electrons surround the nucleus. Protons (+), Neutron (0), Electron (-).
The atom with 55 protons
The name is Cesium, and the symbol is Cs.
The atom with 24 electrons
The name is Chromium, and the symbol is Cr
Element with atomic number 9
The name is Fluorine, and the symbol is F.
The element with atomic number 26 and mass number 58
The name is Iron, and the symbol is Fe.
The element with atomic number 15
The name is Phosphorus, and the symbol is P.
A liquid has a fixed volume but not a fixed shape.
True
Almost all the mass of an atom is concentrated in the nucleus.
True
An empirical formula tell us which elements are present in a compound and gives us the simplest, whole-number ratio of the atoms of these elements in the compound.
True
Atoms X, Y, Z, and R have the following nuclear compositions: Which two are isotopes?
X & Z
A chemical reaction will result in
a different compound
The elements in a column of the periodic table are known as
a group
Determine whether each of the following substances is an element, an ionic compound, a molecule, or a mixture: Baking powder contains 26-30% sodium hydrogen carbonate, and 30-35% calcium dihydrogen phosphate by mass
a mixture
Determine whether each of the following substances is an element, an ionic compound, a molecule, or a mixture: Cytosine, a component of DNA, consists of H, C, N, and O atoms bonded in a specific arrangement
a molecule
Determine whether each of the following substances is an element, an ionic compound, a molecule, or a mixture. Sulfur:
an element
Determine whether each of the following substances is an element, an ionic compound, a molecule, or a mixture. Calcium chloride:
an ionic compound
An ionic compound is formed between____and ____
cation; anion
Does the following statement describe a physical change or a chemical change? 2.0 L of hydrogen gas combines with 1.0 L oxygen gas to form 2.0 L of water vapor.
chemical reaction that forms water from oxygen and hydrogen
The substance, CoCl2, is useful as a humidity indicator because it changes from pale blue to pink as it gains water from moist air. What is its name?
cobalt(II) chloride
Which of the following is a metalloid? carbon, C, Z = 6 sulfur, S, Z = 16 germanium, Ge, Z = 32 iridium, Z = 77 bromine, Br, Z = 35
germanium, Ge, Z = 32
What do we call the columns of elements on the periodic table?
groups
Which isotope of hydrogen has two neutrons?
hydrogen-3
There are 4 naturally occurring isotopes of lead: 204, 206, 207 and 208. Give the number of protons, neutrons and electrons for each.
lead (Pd) 204: p: 82, n:122, e: 82 lead (Pd) 206: p: 82, n:124, e: 82 lead (Pd) 207: p: 82, n:125, e: 82 lead (Pd) 208: p: 82, n:126, e: 82
A molecular compound is formed between___ and ____
nonmetal; nonmetal
What quantity does the mass number minus the atomic number represent?
number of neutrons
How many protons and electrons are present in P^3+
protons: 15 electrons: 12
How many protons and electrons are present in S^1-
protons: 16 electrons: 17
How many protons and electrons are present in Ca^2+
protons: 20 electrons:18
How many protons and electrons are present in Br
protons: 35 electrons: 35
In a neutral atom, what number equals the number of electrons?
the atomic number (protons)
