Chemistry Practice Midterm

Calculate the mass of 0.447 moles of iron. The molar mass of iron is 56.0 g/mol. a. 25 g b. 0.25 g c. 50 g d. 125 g e. None of the above

a. 25 g

A natural sample of an element is found to consist of two isotopes with masses and abundances as listed below: Isotope Mass (amu) Fractional Abundance 1 34.97 0.7577 2 36.97 0.2423 What is the average atomic mass of this element? a. 35.45 b. 36.49 c. 35.00 d. 36.03 e. None of the above

a. 35.45

How many total atoms are there in one formula unit of sodium carbonate: Na2CO3? a. 6 b. 7 c. 4 d. 10 e. None of the above are correct

a. 6

Knowing that oxygen is in Group VI, what charge would you expect to find on the oxide ion? a. -4 b. -2 c. -6 d. +8 e. None of the above

b. -2

Pick the set of three numbers below that represent the actual number of protons,neutrons, and electrons in a cadmium atom. 113 Cd 48 (Order of numbers in answers = p, n, e) a. 24, 65, 24 b. 48, 65, 48 c. 48, 113, 48 d. 48, 65, 65 e. None of the above

b. 48, 65, 48

Which two organic functional groups are part of the following molecule? HOCH2CH2CH2COOH a. Alcohol and aldehyde b. Alcohol and acid c. Acid and ketone d. Aldehyde and ketone e. None of the above

b. Alcohol and acid

Molar masses of three elements are as follows: potassium, 39.10 g/mol; fluorine, 19.00 g/mol; and carbon, 12.01 g/mol. Avogadro's number is 6.022 x 1023 atoms per mole. A researcher has 78.20 g of potassium in her lab. Which of the following is not characteristic of this sample? a. It contains 1.204 x 1024 atoms of potassium. b. It contains the same number of moles of atoms as there are in 19.00 grams of fluorine. c. It contains the same number of moles of atoms as there are in 24.02 grams of carbon. d. It equals twice the molar mass of potassium. e. None of the above

b. It contains the same number of moles of atoms as there are in 19.00 grams of fluorine.

Atomic number and mass number differ in that atomic number is the number of____________ and the mass number is the number of_____________ in an atom's nucleus. a. Protons; protons and electrons b. Protons; protons and neutrons c. Neutrons; neutrons and protons d. Electrons; protons and electrons e. None of the above

b. Protons; protons and neutrons

What is the mass in grams of a sample of graphite containing 5.01 x 1022 carbon atoms? N = 6.02 x 1023 carbon atoms/mole, one mole of carbon weigh 12.0 g a. 144 g b. 12.0 g c. 1.00 g d. 6.02 x 1023 g e. None of the above

c. 1.00 g

Organic molecules all contain one particular element: a. Boron b. Methane (CH4) c. Carbon d. Nitrogen e. Argon

c. Carbon

Which of the following forms of carbon is often given as a sign of love and commitment? a. Graphite b. Charcoal c. Diamond d. Soot e. All of the above

c. Diamond

Identify the atom in the list below that is an isotope of chlorine-37. a. The atom with 37 protons and 40 neutrons. b. The atom with 18 protons and 18 electrons. c. The atom with 20 more neutrons than protons where p = 17 d. The atom with the same number of protons as argon. e. None of the above

c. The atom with 20 more neutrons than protons where p = 17

Atoms that are isotopes have: a. The same number of neutrons, different number of electrons b. The same number of electrons, different number of protons c. The same number of protons, different number of neutrons d. The same number of neutrons, same number of protons e. None of the above

c. The same number of protons, different number of neutrons

Phosphorus has 5 valence electrons and oxygen has 6 valence electrons. How many total valence electrons are there in phosphorus pentoxide, P2O5? a. 30 b. 34 c. 7 d. 40 e. 14

d. 40

Calculate the molar mass of phosphoric acid, H3PO4. The molar mass of H is 1.00 g/mol, P is 31.0 g/mol, and O is 16.0 g/mol. a. 66.0 g/mol b. 50.0 g/mol c. 48.0 g/mol d. 98.0 g/mol e. None of the above

d. 98.0 g/mol

a. Boron b. Methane (CH4) c. Carbon d. Nitrogen e. Argon 2 points QUESTION 23 The formula for ammonium is: a. N2 b. NH3 c. NH2- d. NH4+ e. None of the above

d. NH4+

Which of the following elements has a completely filled valence shell? a. H b. Be c. Zn d. Ne e. None of the above

d. Ne

How many single bond pairs does the nitrogen atom in NH3 form? a. 0 b. 1 c. 2 d. 3 e. 4

d. 3

What is the formula for the carboxylic acid functional group? a. C=O b. -CH2OH c. -CHO d. -OH e. -COOH

e. -COOH

Many of the atoms in covalently bonded molecules tend to form structures in which they have a stable arrangement of electrons. This is often called: a. A noble gas arrangement b. An octet c. Eight pairs of electrons d. Both (a) and (c) are correct e. Both (a) and (b) are correct

e. Both (a) and (b) are correct

Which of the following pairs of atoms will form a covalent bond? a. Mg-O b. C-Cl c. Na-Cl d. N-S e. Both (b) and (d) are correct

e. Both (b) and (d) are correct

Which of the following is not a mixture? a. Blood b. Milk c. Mineral water d. Air e. Hydrogen

e. Hydrogen

One gram of water can be raised one degree Celsius by one calorie of energy. This property is known as: a. Calorie counting b. Temperature c. Fluidity d. Reaction energy e. Specific heat capacity

e. Specific heat capacity