Chemistry Midterm

What is the oxidation state of bromine in bromic acid, HBrO3?

+5

1 tsp of baking soda, NaHCO3, weighs 5.0 g. How many moles of baking soda are in 1 tsp?

0.060 mol

Hydrochloric acid, HCl, is frequently used for titrations, but making a precise molarity of HCl is very difficult. Instead, an approximate solution of HCl is made and then analyzed by titration with sodium hydroxide to determine its precise molarity. The titration reaction is HCl + NaOH NaCl + H2O. If 27.29 mL of 0.0989 M NaOH is required to titrate 25.00 mL of HCl, what is the molarity of the HCl?

0.108 M HCl

How many moles of nitric acid, HNO3, are in 175 mL of a 2.75 M solution of nitric acid?

0.481 mol

What is the answer to 5.763 x 0.111 ÷ 1.2, reported to the correct number of significant figures?

0.53

How many moles of phosphoric acid, H3PO4, are in 150 mL of a 4.25 M solution of phosphoric acid?

0.638 mol

The molecular mass of CH4O is the sum of the masses of

1 C atom, 4 H atoms, and 1 O atom

Calcium chloride in an ionic compound that readily absorbs water from the atmosphere and is commonly used inside drying tubes in lab experiments to prevent atmospheric water from interfering with reactions. How many ions of calcium and chlorine does each molecule of calcium chloride contain?

1 calcium ion, 2 chlorine ions

Magnesium nitrate is an ionic compound that is commonly used as a plant fertilizer. How many magnesium ions and nitrate ions does each molecule of magnesium nitrate contain?

1 magnesium ion, 2 nitrate ions

Vienna Standard Mean Ocean Water (V-SMOW) is a common reference material when making hydrogen isotope measurements. Analysis of V-SMOW shows that it is 0.015576% 2H (mass 2.01410 amu) and the remainder is 1H (mass 1.00782 amu). What is the average mass of hydrogen in V-SMOW?

1.00798 amu

A 500 mL bottle of water contains 27.75 mol of water. How many molecules of water are in the bottle?

1.67 x 10^25 molecules

The molecular mass of the amino acid valine, C5H11NO2, is

117.15 amu

What volume of 1.97 M HCl is needed to prepare 50.0 mL of 0.50 M HCl?

12.69 mL

How many grams of NaF are in 250 mL of a 1.23 M solution?

12.9 g (.250Lx1.23M/1L)=.3075mol .3075molx41.99g =12.9g

What is the answer to 117.3 + 4.291 - 0.09, reported with the correct number of significant figures?

121.5

What volume of 2.17 M HCl is needed to prepare 125.0 mL of 0.25 M HCl?

14.4 mL

Distillation analysis of a wine sample shows that a 25.0 mL sample contains 3.70 mL of ethanol. What is the percentage of ethanol in the sample?

14.8 (v/v)%

The formula mass of calcium bicarbonate, Ca(HCO3)2, is

162.12 amu

One mol of ammonium sulfate, (NH4)2SO4, contains

2 moles of ammonium ions

How many millimeters are in 0.24 km?

2.4 x 10^5 mm

In the reaction O2(aq) + 4KI(aq) + 2H2SO4(aq) 2I2(aq) + 2H2O(l) + 2K2SO4(aq), how many moles of KI are required to react completely with 0.676 mol of O2?

2.70 mol

If 2.8 g of hydrogen gas and 19.6 g of oxygen gas are reacted to make water, 2H2(g) + O2(g) 2H2O(g), how many grams of H2O can be produced and what will be the limiting reactant?

22 g of H2O, O2 will be limiting

44Ca has

24 neutrons

The density of platinum is 21.45 g/cm^3. What is the volume in cm^3 of 1.27 pounds of platinum?

26.9 cm^3

Nitrogen monoxide gas reacts with diatomic oxygen to produce nitrogen dioxide gas. What is the balanced chemical equation?

2NO(g) + O2(g) 2NO2(g)

In the photosynthesis reaction 6CO2 + 6H2O C6H12O6 + 6O2, how many moles of CO2 will be needed to produce 3 moles of O2?

3

One mole of the antibiotic medicine amoxicillin, C16H19N3O5S, contains

3 moles of N atoms

A hydroponic fertilizer solution contains 55.4 ppm of calcium in water which is equivalent to 55.4 mg/L. What is the total mass of calcium in 65 L the fertilizer solution?

3.60 g

Oleic acid, the most abundant fatty acid in olive oil, has a molecular formula of C18H34O2. How many hydrogen atoms are in oleic acid?

34

Distillation analysis of a beer sample shows that a 15.0 mL sample contains 0.71 mL of ethanol. What is the percentage of ethanol in the sample?

4.7 (v/v)% (volume of solute/volume of solution x100%)

In the combustion of ethane, 2C2H6 + 7O2 4CO2 + 6H2O, what mass of CO2 will be produced from 15.2 g of C2H6?

44.5 g

How many grams of NaF are in 150 mL of a 1.19 M solution?

7.50 g

If the theoretical yield for a reaction is 0.271 mol but only 0.194 mol is actually produced, what is the percent yield for the reaction?

71.6%

An ion of Tungsten has a mass number of 184 and contains 68 electrons. How many protons and neutrons does it contain, and what is its charge?

74 protons, 110 neutrons, charge is +6

Stoichiometry

All of the other answer choices are correct.

What is formed when an atom or molecule gains an electron, resulting in a negative charge?

Anion

Analysis of a sample of an unknown liquid shows that it is 83.6% C and 16.4% H. What is the empirical formula of the unknown?

C3H7

Sorbitol is a sugar alcohol that is commonly used to sweeten "Sugar-Free" foods, though it still has the same number of calories per gram as regular sugars. A molecule of sorbitol has 6 carbon atoms, 14 hydrogen atoms, and 6 oxygen atoms. What is the empirical formula of sorbitol?

C3H7O3

The reaction of citric acid and sodium bicarbonate, C6H8O7 + 3NaHCO3 3CO2 + 3H2O + C6H5O7Na3, is used to make bath bombs fizz when added to water. If a bath bomb is made with 1 mol of C6H8O7 and 4 mol of NaHCO3,

C6H8O7 will be the limiting reactant

Fluorite is a mineral and semi-precious gemstone with the chemical formula CaF2. What is the chemical name of this compound?

Calcium fluoride

In the atmospheric reaction Cl(g) + O3(g) ClO(g) + O2(g). What is Cl(g) + O3(g)?

Cl(g) and O3(g) are both reactants

Which of the following is a physical change?

Condensation forming on a window

What is the name of B2O3?

Diboron trioxide

What is outside an atom's nucleus and has a negative charge?

Electron

A pure substance that cannot be broken down into simpler substances by chemical changes is a/an

Element

What is the formula for mercury(II) nitrate dihydrate?

Hg(NO3)2 · 2H2O

A tentative explanation of observations is a/an

Hypothesis

What has the same chemical formula, but different chemical properties?

Isomers

A Class-A 10 mL pipette is supposed to dispense 10.00 mL of water. A lab technician makes three measurements of the volume that the pipette actually dispenses, and obtains volumes of 10.21 mL, 9.73 mL, and 10.14 mL. The pipette is

Neither precise or accurate

What is the name of N2O3?

Nitrogen trioxide

Use a table of soluble and insoluble ionic compounds to predict the precipitate that will form in the reaction of Ca(NO3)2(aq) + Na2(SO4)

Only Ca(SO4) will precipitate

What information is needed to calculate the molarity of an acetic acid solution?

Only the number of moles of dissolved acetic acid and the volume of the solution

What information is needed to calculate the molarity of a glucose solution?

Only the number of moles of dissolved glucose and the volume of the solution

In the reaction of KCl and Pb(NO3)2, the net ionic equation is

Pb2+(aq) + 2Cl-(aq) PbCl2(s)

The three naturally occurring isotopes of neutrally charged oxygen atoms have:

The same number of protons, but different number of neutrons

True or False: One mole of gold contains the same number of atoms as one mole of silver

True

The number of decimal places in the answer will equal the fewest decimal places in a number in the calculation

When adding or subtracting measurements

What expands to completely fill a container?

a gas

Covalent Bonds

are formed when electrons are shared between atoms

Ionic compounds

are typically formed between a metal element and a non-metal element

Oxidation involves

both a loss of electrons and an increase in oxidation number

The term "molecular mass"

can only be correctly used to describe the mass of a neutral molecule

Aqueous solutions

contain water as the solvent

A strong base

dissociates completely to yield hydroxide ions when dissolved in water

Chlorine is most likely to

gain 1 electron to form an ion with a -1 charge

A solution

is a homogeneous mixture

Boron has an average atomic mass of 10.81 amu and has two naturally occurring isotopes. The most abundant isotope has 5 protons and 6 neutrons, so the less abundant isotope must have

less than 6 neutrons

Potassium is most likely to

lose 1 electron to form an ion with a +1 charge

If the volume of an initial solution is doubled, the concentration of the final solution will be

one half the concentration of the initial solution

If the volume of an initial solution is tripled, the concentration of the final solution will be

one-third the concentration of the initial solution

2AgNO3(aq) + BaCl2(aq) 2AgCl(s) + Ba(NO3)2(aq) is an example of a

precipitation reaction

The actual yield for a reaction is

the amount of product that is obtained by a reaction, based on a measurement

In the unbalanced reaction of Fe(s) + O2(g) Fe2O3(s)

the coefficient for Fe(s) will be 4 when balanced

In the reaction 2Al(s) + 6HCl(aq) 2AlCl3(aq) + 3H2(g)

the oxidation state of Al changes from 0 to +3, and Al is oxidized

The mass percentage of a solution is

the ratio of the mass of the solute to the mass of the solution

The mass-volume percentage of a solution is

the ratio of the mass of the solute to the volume of the solution

To analyze the acidity of orange juice, an acid-base indicator is added to a sample of the juice and NaOH is added until the indicator changes color. This is an example of

titration analysis

Household ammonia is typically a solution of 5% NH3 and 95% water. In household ammonia, what is the solvent and what is the solute?

water is the solvent and NH3 is the solute

Seawater is a solution of approximately 3.5% NaCl and 96.5% water. In seawater: What is the solvent and solute?

water is the solvent and NaCl is the solute