DAT Chemistry

what is the EN range for polar molecules?

0.4-1.7 if lower- nonpolar, if higher- ionic

what's the percent yield for a reaction in which 27 g of Cu is produced by reacting 32.5g of Zn in excess CuSO4 solution copper mm 63.5 g/mol, zinc's 65g/mol, sulfur 32g/mol, oxygen 16 g/mol?

1. draw balanced equation 2. calculate theoretical yield 3. determine percent yield actual / theoretical yield= 27g/32g x100%= 84% Pg320

How many valence electrons does hydrogen cyanide have?

10 (HCN) H=1 C=4 N=5

Balance the redox Ron between MnO4 and I in an acidic solution MnO4- + I- ---> I2 + Mn2+

10 I- + 16 H+ + 2MnO4- --- 5I2 + 2Mn2+ + 8 H2O pg. 341 for steps

If 10g of NaOH are dissolved in 500g of water, what is the molality of the solution (the molecular mass of NaOH is 40 g/mol)?

10g NaOH / 40 g/mol NaOH = 0.25 mol 0.25mol NaOH / 0.5 kg of H2O= 0.5 molality NaOH

from the reaction CaCl2 + 2H2O --> Ca(OH)2 + C2H2 How many grams of C2H2 are formed from 0.400 moles of CaCl2?

26 g/mol of C2H2 x 0.40 mol of CaCl2= 10.4 g see pg 321

How many grams of calcium chloride are needed to prepare 72g of silver chloride according to the following equation (calcium mm 40 g/mol, chlorine's is 35.5 g/mol, and silver is 108 g/mol. CaCl2 (aq) + 2AgNO3 + --> Ca(NO3)2 + 2AgCl

27.5g of CaCl2 is needed to produce 72g of AgCl see pg318

what is the mass of a single O2 molecule?

32g / 6.022x10^23= 5.31x10^-23 g pg.325

How much NaOH must be added to 200mL of water to male a 1.0 M NaOH solution? (mm= 40.008)

40g of NaOH is 1 mol. so 40g of NaOH dissolved in 1 L of water is a 1 M solution of NaOH. so the equation is as follows: x / 200mL = 40g / 1,000mL (converting from 1 L) x= 200 mL(40g NaOH) / 1,000mL 8g of NaOH is needed

How many mL of a 5.5 M NaOH solution must be used to prepare 300 mL of a 1.2 M NaOH solution?

5.5M x V1 = 1.2 M x 300 mL= 65 mL

What is Avagadro's number?

6.02x10^23 units/mol

from the equation: 2NF3 + 3H2O --> 6HF + NO + NO2 How many grams of HF are expected to form if 1500g of 5.2% NF3 sample is used?

78g NF3 / 71g/mol (NF3) x 3 x 20 g= 65.92g HF

How many moles are in 9.52g of MgCl2?

9.52g / 95.21 g/mol= 0.10 moles Cl2= 71 amu + 24.305 amu = Mg

Which of the following combinations is most suitable for titrating and measuring the pH of a solution with an endpoint of pH 4.4? A. Buret, beaker, and litmus paper B. Pipet, Erlenmeyer flask, and litmus Paper C. Buret, Volumetric flask, and pH meter D. Pipet, volumetric falsk, pH meter E. Pipet, Erlenmeyer flask, and pH meter

A. a buret is the preferred dispensing glassware for a titration since it allows the titrant to be gradually dispensed so the pH can be monitored. Litmus paper isn't the most accurate but it will change color almost exactly at the desired pH point Use of a beaker makes it easy to check pH

Which if the following has the lowest EN? A. Cs B. Sr C. Ca D. B E. P

A. cesium

Balance the following equation: Al(s) + HCl(aq)--> AlCl3(s) + H2(g)

Al(s) + 3HCl(aq)--> AlCl3(s) + 3/2 H2(g)

Is Cl- and anion or a cation

Anion

a simple cake icing can be made by dissolving a large quantity of sugar (sucrose) in boiling water, cooling the solution, and applying it to the cake before it reaches room temp. The icing appears to harden as it cools in part because A. Common ion effect limits the dissolution of sucrose B. Sugar concentration increases as water boils off, and the solubility of sugar in eater decreases as the solution cools C. Sucrose molecules dissociate to form fructose and glucose, which are insoluble in water

B

which terms describes when an electron jumps from its ground state to a higher energy level A. Balmar Series B. Atomic absorption spectrum C. Lyman Series D. Atomic emission spectrum

B

If the principal quantum number of a shell is equal to 2, what types of orbitals will be present? A. s B. s and p C. s, p, and d D. s, p, d, and f

B because of the equation 2n^2 you'd have 8 which goes up to the p orbital

Which of the following will be the most electrically conductive? A. Sugar dissolved in water B. Saltwater C.Salt dissolved in organic solvent D. Pure water

B saltwater because NaCl is an ionic compound. Only ionic compounds (electrolytes) dissolved in polar solvents will conduct electricity. Sugar water is covalent not ionic, C and D aren't right b/c salt won't dissolve nicely in organic solvents and pure water doesn't water any electrolytes in it so it can't conduct electricity.

A student represents electrons within the same orbital as having parallel spins. This goes against which principle? A. Bohr's model of Hydrogen B. Pauli exclusion principle C. Heisenburg's uncertainty principle D. Planck's quantum theory E. Aufbau principle

B.

The Mg2+ ion has how many electrons? A. 12 B. 10 C. 14 D. 15 E. 8

B. 10 Magnesium has an atomic number of 12 meaning it has 12 protons and 12 electrons. however it has a 2+ charge so it actually has 10 electrons

Which of the following choices correctly describes the solubility behavior of potassium chloride (KCl)? a. Solubility in CCL4 > Solubility in CH3CH2OH > Solubility in H2O b. Solubility in H2O > Solubility inCH3Ch2OH > Solubility in CCL4 c. Solubility in H2O > Solubility in CCl4 > Solubility in CH3Ch2OH

B. because KCl is an ionic salt so it is soluble in polar molecules and insoluble in non polar molecules. water is highly polar. ethyl alcohol has that OH bond so it is slightly polar, but CCl4 cancel each other out making them non polar.

which of the these represent excited state of scandium? A. 1s2 2s2 2p6 3s2 3p6 3d1 4s2 B. 1s2 2s2 2p6 3s2 3p6 3d2 4s1

B. scandium has 21 e- and in the excited state it will first fill the lower energy orbital first.

why does fluorine have a constant oxidation number?

Because it's the most EN

water (H2O) would have what kind of geometric shape and angle?

Bent geo. and 104.5 angle

What is the best piece of glassware to use to transfer exactly 50mL of liquid A. 50mL beaker B. 50mL Erlenmeyer flask C. 50 mL volumetric pipet D. 50 mL Volumetric flask E. 500mL graduated cylinder

C because it is specially made to perfectly transfer 50mL unlike D which is made to hold that much liquid

In Bohr's model of hydrogen atom, the energy of an electron is directly dependent on A. spin quantum constant (m_s) B. Planck's constant (h) C. Principal quantum number (n) D. angular momentum quantum number (l)

C. because the equation is E= -R*y/n^2 where here the Ry is constant

Elements in a given period have the same A. atomic weight B. maximum azimuthal quantum number C. maximum principal quantum number D. valence electron structure

C. maximum principal quantum number

rank the following increasing to boiling points CH3OH, LiF, C2H6, HCl

C2H6< HCl<CH3OH< LiF C2H6= London force HCl= dipole-dipole CH3= hydrogen bonding LiF= ionic

which of the following will provide the most accurate and precise measurements of a sample at approximately pH 5? A. pH meter calibrated at pH 5.00 B. pH meter calibrated at pH 4.01 and pH 10.0 C. pH meter calibrated at pH 7.00 D. pH meter calibrated at pH 7.00, 4.01, and 10.0 E. Litmus Paper

D because it's better the have a three point calibration test and it's always better than litmus paper

Which of the following is appropriate to use fr a procedure that involves simultaneously heating and distilling a reaction mixture? A. Erlenmeyer flask B. Erlenmeyer fast with a hose barb C. Volumetric flask D. Round-bottom flask E. Either A or B

D. because its round shape gives it extra strength to withstand heat

what is the sign that represents heat in a chemical reaction

Delta

you'd say a solution is _____ when solvent is added to a solution of higher concentration to produce a solution of lower concentration.

Diluted

Neutralization reactions are a type of single or double replacement reactions

Double

how do you calculate electromagnetic energy?

E- Energy h- Planck's constant (6.626x10^-34 J*s c- velocity of light in a vacuum(3.00x10^8 m/s) y- wavelength

the maximum number of electrons in a shell with a principle quantum number of 4 is A. 2 B. 6 C. 10 D. 16 E. 32

E. for quantum numbers use the equation 2n^2 which in this case would equal 32

The photon frequency of red light is 4.51x10^14 s-1. If Ry= 2.18x10^-18, what's the energy of the photon?

E= hv E= (6.626x10^-34 J*s)(4.51x10^14 s-1) = 2.988x10^-19 J (energy of photon)

the Ca2+ species is electronically similar to the elements in A. Group IIA B. Group IA C Group IVB D Group 0

Group 0 because its outermost valence shell is a complete octet. It is isoelectronic to argon

is the HF bond more or less polar than the H-H bond

H-H bond is non polar and the HF bond is very polar due to the unequal sharing of electrons

Name the compound HCO3-

Hydrogen carbonate

Name the compound ClO-

Hypochlorite

what is the oxidation states for group IA and IIA?

IA= +1 and IIA= +2

As you go from left to right and from down to up, EN ___, ionization energy ____, and atomic radius ____ (increase or decrease)

Increase, increase, decrease

Atoms with the same atomic number but different mass number are called what

Isotopes

How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain?

It would have 50 protons and neutrons, and (125 - 50)= 75 electrons

what does Potassium Nitrite look like

KNO2

name the compound Li2SO4

Lithium sulfate

what are the four intermolecular forces and arrange them weakest to strongest

London force (weak) dipole-dipole hydrogen bond dipole-ion (strong)

name the compound MgSO3

Magnesium sulfite

Is Silicon a metal, nonmetal, or metalloid?

Metalloid

which of the following would you expect to be weakly drawn to a magnetic field? H2, NaCl, NO, NO2, BF3

NO (11 v.e.) or NO2(17v.e.) because they have an odd number of valence electrons which makes them paramagnetic. Paramagnetic compounds are weakly drawn to magnetic fields

Name the compound NO2-

Nitrite

can you determine the molecular formula of a specific molecule with the empirical formula only?

No it's not possible because several different molecules could share the same empirical formula (ex. CH2 could be C2H4 or C4H8)

what is the order in increasing electron affinities from the following: Alkaline earth metals, Noble gases, halogens?

Noble Gases, Alkaline earth, halogens

Name the compound ClO4

Perchlorate

the atomic ____ of a chemical element is about ____ the distance between the centers of two atoms of the element

Radius; one half

what are the reducing and oxidizing agents, oxidation numbers, SnCl2 + PbCl4--> SnCl4 + PbCl2

Sn goes from +2 to +4 (oxidized and reducing agent) Pb goes from +4 to +2 (reduced and oxidizing agent)

name the compound NaClO

Sodium hyperchlorate

name the compound NaClO4

Sodium perchlorate

Name the compound SO4 ^2-

Sulfate

PCl5 would have what kind of geometric shape and angle?

Trigonal bipyrimidal geo. and 90, 120, and 180 angle

electrons in the electron shell farthest from the nucleus are known as what?

Valence electrons

what's the formula for percent composition in a compound?

X mass of element / overall compound mass *100%

What should be used to titrate 50mL of 0.1 N HCl with 0.2 N NaOH? A. 10mL buret B. 30mL buret C. 30mL graduated pipet D. 50mL volumetric pipet E. 50mL graduated cylinder

You must first calculate how much NaOH you'd need: N1V1=N2V2 -> (50mL)(0.1 N) / (0.2 N)= V2= 25mL so it would be B because a buret is the best instrument to use.

How would you fund the molecular mass of SOCl2? what is the molecular mass?

You'd add up the individual atomic masses of each molecule. 1S= 32 amu 1O = 16 amu 2Cl = 71 amu = 119amu

in going from --3s23p64s1 to --3s23p54s2 an electron would a. absorb energy b. emit energy c. relax to the ground state d. bind to another atom

a absorbs energy

what group of salts are always soluble in water?

alkali metal ions (Li, Na, K, Rb, Cs, Fr)

what group of metals are insoluble

all metal oxides like ClO is insoluble. However if placed with any alkali, it's made soluble

what does it mean if a molecule is paramagnetic

all paramagnetic molecules will have an odd number of valence electrons. Paramagnetic compounds are always weakly drawn to magnetic fields

what does the law of Constant composition state?

all samples of a given compound will contain the same elements in identical mass ratios

what is the oxidation number

an atom is the charge that atom would have if the compound was composed of ions. of simple ions is equal to the charge on the ion

The order of elements in the periodic table is based on A. number of neutrons B. radius of the atom C. atomic number D.atomic weight

atomic radius

how would you describe a decomposition reaction

break down of one substance into simpler parts

the net positive charge from the nucleus, as felt by an electron is known as what

effective nuclear charge

The change in energy that occurs when an electron is added to an atom is...

electron affinity

what's the difference between empirical and molecular formulas

empirical gives the simplest whole number ratio of the elements in a compound molecular gives the exact number of atoms of each element in a compound

what are the empirical and molecular formulas of a compound that contains 40.9% carbon, 4.58% hydrogen, and 54.52% oxygen. Molecular mass is 264 g/mol (C mm= 12g/mol H mm= 1g/mol O mm=16g/mol)?

empirical= C2H4O3 molecular= C9H12O9 Pg317

what quantity of energy is emitted when a hydrogen electron relaxes from n=3 to n=2? (Ry= 2.18x10^-18 J)

equation : Ry ((1/n1^2) - (1/n2^2)) 2.18x10^-18 J ((1/9) - (1/4)) 2.18x10^-18 J (4/36 - 9/36) 2.18x10^-18 J (-5/36)= 3.03x10^-19 J The value of energy is positive because energy is released when an electron is released and e- falls from higher to lower state

true or false: all salts with ammonium ion (Nh4+) are NOT soluble

false, any compound with NH4+ are soluble

Where are metalloids located on the periodic table?

found along diagonal line between metals and nonmetals

explain why the group 0 elements are so unreactive

group 0 are the noble gases which the outermost shell contain complete, stable formations. There is no reason for these elements to attempt to gain or lose electrons because stable on their own

How many protons, electrons, and neutrons does an 58Ni have?

has an atomic number of 28 and a mass number of 58. So it would have 28 protons, 28 electrons, and (58-28)= 30 neutrons

How many protons, electrons, and neutrons does an 60Ni2+ have?

it would have 28 protons, 26 electrons, and 32 neutrons

It is shown the ratio of naturally occurring chlorine-35 to chlorine-37 is 3:1. What is the standard atomic weight of Chlorine?

knowing the ration means that it is 25% chlorine-37 and 75% chlorine-35: (0.25*37g/mol) + (0.75*35g/mol)=35.5 g/mol

If 28 g of Fe are reacted with 24 g of S to produce FeS, what is the limiting reagent? How many grams of excess reactant are present in the vessel at the end of the reaction?

mass of S= (0.25 mol S) 32g/ 1 mol S = 8g of S see pg 319

Is francium (Fr) a metal, nonmetal, or metalloid?

metal

what groups are always insoluble?

metal oxides, hydroxides (containing OH-), and salts with carbonates (CO3 2-). exceptions include alkali metals

Is Boron a metal, nonmetal, or metalloid?

metalloid

what are the properties of metalloids

metalloids are elements that when undergoing a reaction, act as either metals or nonmetals depending upon the species with which they are reacting. (ex. boron, silicon, arsenic)

Discuss the properties of metals and give four examples of metallic elements

metals have high melting points and densities. and they lose electrons very easily

how many moles of salicylic acid (C7H6O3) should be used to prepare six-5grain aspirin (C9H8O4) tablets? (1g=15.5 grains)

mm of aspirin 180.123 g/mol 1.94g/180.123 g/mol= 0.11mol

what's the formula for finding the number of moles present?

mol= weight of sample (g) / Molar weight (g/mol)

Determine the molecular formula and calculate the percent composition of each element present in nicotine, which has an empirical formula of C5H7N and a mol. mass of 162 g/mol

molecular formula C10H14N2 percent= C=74% H=8.7% N=17.3% see pg 323

to balance a redox reaction, both the _______ and the ______ must be equal on both sides

net charge and number of atoms

The Pauli exclusion principle states what about quantum numbers

no two electrons can have the same four quantum numbers

Is phosphorus a metal, nonmetal, or metalloid?

nonmetal

when would the oxidation state of Group VIIA elements not be -1?

only when they're paired with something of higher EN. Ex.) in HCl oxidation for H is -1 but on HOCl oxidation is +1 because O is more EN and oxidation number is -2

If an element is losing electrons in a half reaction you'd say that the element is being ___

oxidized (LEO says GER) Losing electrons oxidation, Gaining electrons reduction

single-displacement reaction are often further classified as ___ reactions

redox

Periods are ____ and groups are ___ on the periodic table

rows; columns

What is the difference between single and triple bonds in terms of bond length and bond energy

single (longest length, lowest energy)<easy to break triple (shortest length, highest energy)< hard to break

what is the normality of a 2.0 M solution of phosphoric acid, H3PO4, for an acid-base titration?

there's 3 moles of hydrogen for each mole of H3PO4 (acid based) so 2 M x 3N /1 M = 6N

what are the two ways to express a formula for a compound

through the empirical formula and the molecular formula

True or false: SO4 2- is soluble but if placed with Ca2+ or Pb2+ makes it insoluble

true

true or false: salts with chloride (Cl-), bromide (Br-), Iodide (I-) are water soluble while salts with Ag+, Pb2+, and Hg2 2+ are insoluble

true, AgCl is insoluble

how would you describe a combination reaction

two reactants forming a bond to create a molecular product.

if 92g of glycerol is mixed with 90g of water, what will be the mole fraction of the two components (mm of water = 18g/mol and glycerol is 92 g/mol)?

water= 5 moles and glycerol 1 mole =6 total moles. X(water)= 5/6 mol= 0.833 mol x(glycerol)= 1/6 mol= 0.167 mol 0.833 + 0.167= 1

when would a neutralization reaction occur?

when an acid reacts with a base to produce a solution of a salt and water

when will oxygen have an oxidation number other than -2?

when paired with a more EN element. Ex. OF2, in this case oxygen would have +2 oxidation state

Can hydrogen have +1 and -1 oxidation number? why or whynot?

yes it can naturally it's +1 but if paired with a less EN element.