Chem Test 2

How many moles of sodium chloride are there in 250 mL of a 1.20 M sodium Chloride solution?

0.30

If the lead of concentration in water is 1 ppm, then we should be able to recover 1 mg of lead from ____ L of water

1 (ppm=mg/L)

What is the molarity of sodium chloride in a solution containing 0.50 mol of sodium chloride in 500 mL of water?

1.0 M

Which corresponds to the composition of the ion typically formed by magnesium?

12 protons 10 electrons 2+

A 4-L sample of water contains 80 micrograms of lead. What is this lead concentration, in parts per billion?

20

How many bromide ions can combine with one ion of aluminum to form an ionic compound?

3

Numbers 1 through 4 are used to identify four different elements. Based on periodic table trends, which number identifies the element that is expected to have the greatest tendency to attract a shared pair of electrons?

3 (Halogens)

The recommended daily requirements of calcium is 1000 mg. Tap water in a Midwestern city contains approximately 150 mg Ca/L. A person living in the city who drinks two liters of water in one day would receive ____ percent of his/her RDA of calcium

30

How many joules are required to heat 2.0 L of water from 20 C to its boiling point of 100 c. The specific heat of water is 4.18 and the density of water is 1 g/mL

6.7 x 10^5 J

A student wants to prepare exactly 250 mL of a 0.500 M aqueous potassium hydroxide solution. What mass of potassium hydroxide must the student dissolve in the 250 mL of solution?

7.01 g

A 2- ion has 36 electrons and 45 neutrons what is its correct symbol?

79Se 2-

Which corresponds to the composition of the ion typically formed by fluorine?

9 protons 10 electrons 1-

What percentage of Earth's water is in the oceans?

97%

What is biological oxygen demand?

A measure of the amount of dissolved oxygen microorganisms use up as they decompose organic wastes found in water

The drawing shows two water molecules. Which statement is correct?

A=covalent bond. B=hydrogen bond A is stronger

What is the correct name for (NH4)2CO3

Ammonium Carbonate

Which shows the lewis structure of water with the correct partial charges and nonbonding electrons?

C. (The negative is on the O and positive on the Hs. Two lone pairs)

which of these is not a trihalomethane?

CH3Cl

Which compound has the correct formula?

CaSO3

Which compounds are NOT soluble in water at room temperature?

CaSO4 and PbCl2

Which form of water disinfection continues to provide antibacterial protection after the water leaves the purification plant?

Chlorination

Which is the correct lewis structure on a chlorine atom and the ion that chlorine forms?

Cl with 7 electrons around it with a negative ion charge

What is the correct name for CuO

Copper (II) Oxide

Which ions if present in drinking water, would pose a significant health risk?

Everything but Ca2+

Which of the following is/are true about Maximum contaminant level goals?

Everything but the MCLG for a contaminant is always set to zero because this is the best way to protect human beings

The MCL for drinking water is the legal limit for the concentration of a contaminant expressed in ppm or ppb. This is always a lower concentration than the MCLG value for the same Contaminant

False

Which covalent bond is the most polar?

H---O

When table sugar dissolves in water, which types of attraction between water and sugar molecules occur?

Hydrogen and Polar-Polar interactions

Which molecule(s) contain(s) polar covalent bonds but is (are) non polar?

I and III only

The world map shows the availability of safe drinking water around the world. Which statement is true?

In the United states and Canada, more than 90% of the populate has access to clean water

What is the formula of the ionic compound formed with magnesium and chlorine?

MgCl2

Which compound has an incorrect formula?

MgPO4

Mixing which of the two following will produce a precipitation reaction (give an insoluble product)?

Na2SO4 and Ba(OH)2

Which of the following has the highest MCL in drinking water in the US

Nitrates

We cannot effectively clean non polar substances from our hands or clothing with water alone; we must add soap or detergent. The structure of a typical soap molecule is shown below. Which region of this molecule would dissolve in a non polar substance such as grease?

Region 1

Which of the following are methods of making sea water appropriate for drinking?

Reverse Osmosis and Distillation

A O.25 M solution of the sugar sucrose C12H22O11, in water is tested for conductivity using the type of apparatus shown. What do you predict will happen?

The bulb will not light up. Sucrose is in the molecular form in aqueous solution

Which best symbolizes the hydrogen bonding between two water molecules?

The last one. (The white one touching the bleach one)

A 0.25 M aqueous solution of potassium chloride, KCl is tested for conductivity using the type of apparatus shown what do you predict will happen?

The light bulb will shine brightly. KCl is highly ionized in aqueous solution

In general, hydrogen bonds are

about 1/10 as strong as typical covalent bonds

Which correctly describes groundwater?

any water taken from aquifers

Which compound is insoluble in water?

calcium carbonate

Which is not a form of chlorine used to disinfect water?

chloroform

The drawing shows simple way of purifying salt water. What is this process called?

distillation

Which type of water may be considered pure?

distilled water

The process of water evaporating from your skin is

endothermic

Which statement is not true?

in forming a solution, the solute dissolves other substances that are called solvents

Water has one of the highest specific heat of any known liquid. This means that the temperature of a water sample _____ with the input of a _____ amount of energy.

increases only slightly; large

The attractions between anions and cations throughout a crystal are known collectively as

ionic bonds

Electronegativity

is a measure of an atom's attraction for an electron in a chemical bond

Potable water is water that

is safe to drink and to cook with

Which of the following is not a consequence of biomagnification?

lead in water can lead to brain damage in children.

What are the major disadvantages of using ozone instead of chlorine to disinfect water?

ozone decomposes quickly and does not provide long term protection against possible contamination as the water is piped through a municipal distribution system

When the ____ molecules of ethanol, C2H5OH are added to water, the ethanol molecules ________

polar; form hydrogen bonds with the non polar water molecules

At water treatment plants aluminum sulfate and calcium hydroxide are added to...

remove suspended clay and dust particles

The fact that carbon (C) is less electronegative than nitrogen means that in a C--N bond, the.....

shared electrons are closer to the N atoms than to the C atoms

Which compound shows be the most soluble in water?

the first one

Which is the best representation showing a sodium cation in water?

the first one with the hydrogen facing out

A disadvantage of ozonation over chlorination is

the higher cost of ozonation and ozonation does not protect the water after the initial process is complete

Which is the best definition of specific heat?

the quantity of heat energy that must be absorbed to increase the temperature of one gram of a substance one degree Celsius

The EPA regulates the presence of nitrates and nitrites in water because

they interact with the blood and limits its ability to transport oxygen

The main reason that water supplies are chlorinated is

to kill disease causing organisms in the water

Reverse Osmosis is illustrated in this diagram. What is this process used for?

to remove dissolved salts from sea water

A polar covalent bond is created when

two atoms share their bonding electrons unequally

Why is water a liquid at room temperature instead of a gas?

water has hydrogen bonds between the molecules

Which is not a consequence of hydrogen bonding between water molecules?

water is colorless and odorless