WGU D425 Introduction to Chemistry

Calculate the density of 10.4mL sample of a substance with a mass of 35.12g. Enter the answer in the correct number of significant figures and include the unit g/mL

convert 12.5g in to kilograms. enter answer in kg

0.0125

calculate the density of an object that has a mass of 19.378 and a volume of 15ml. enter as g/ml

a substance has a mass of 42.10g. if the density of the substance is known to be 2.431g/ml what volume of substance is present

several samples of a metal weighed and placed into a graduated cylinder filled with water to measure their volume by water displacement

several samples of metal were weighed and placed into the graduated cylinder filled water to measure their volume by water displacement q

Dimensional Analysis Ex.

how many centimeters are there in 3.55m

quantity given: 3.55m

3.55m * (100cm/1m)=

3.55m=355cm

Density converted between mass and volume of a substance

30.2ml sample of ethyl alcohol with a mass of 23.71002g

p=23.71002g/30.2ml=0.7851

p=

p=0.785g/ml

Find mass of and object. density of alcohol is 0.7892g/mL, so alcohol is 0.7892g per 1ml. determine the mass of alcohol for 2.0mL use

2.0mL*(0.7892g/1mL)=

1.5784g=1.5g

Density = mass/__________

volume

Density of an object?

mass of 2.4019 and volume of 1.40mL

2.4019g/1.40mL=

density = 1.7156g/mL= 1.72g/ml

Density of an object?

volume of 32mL and a mass of 12.24g

12.24g/32mL

density= 0.3825g/mL=0.38g/mL

density of an object?

mass of 78.2g/14.2cm^3

density= 5.507g/cm= 5.51g/cm^3

density of an object?

22.57cm^3/55g

density= 2.43686g/cm^3= 2.4g/cm^3

density of an object?

85g/35mL

density= 2.42857 g/mL= 2.4g/mL

what is the mass of 25.0mL of octane, with a density of 0.702 g/cm

-Given:25.0mL

conversion factors:

1.1mL

2.0.0702=1cm^3 (mL->cm^3->g)

25.0mL1cm^3/mL0.702g=

density= 17.55g= 17.6g

the density of titanium is 4.51g/cm^3. What is the volume in cubic inches of 3.5Ib of titanium?

conversion factors:

1) 2,2Ib=1Kg

2) 1Kg=10^3g

3) 4.51g= 1cm^3

4) 2.54cm= 1 in Find in^3

Ib-> Kg -> g-> cm^3 -> in^3

3.5Ib 1Kg/2.2Ib10^3g/1Kg1cm^3/4.51g1in/2.54cm

must multiply (1in/2.54cm)^3=1in^3/16.387cm^3

3.5Ib1Kg/2.2Ib10^3g/1Kg1cm^31in^3*16.38cm^3

density= 21.53in^3= 22in^3

Calculate the density in g/mL of aluminum with a volume of 0.6cm^3 and a mass of 4.6mg?

Given: 4.6mg and 0.6cm^3

Formula for Density: mass (g)/volume(ml) Find:

Density:1) mg->g 4.6mg*10^-3g/1mg=

4.6*10^-3g=

2) cm^3->mL 0.6cm^3*1mL/1cm^3=0.6mL

step 1 by step 2

3) Divide g/mL 4.6*10^-3/mL=

Density= 0.008 g/mL

what is the density in g/cm^3 of an unknow solution containing 2.3kg and 8.0L

Density = 0.29g/cm^3

If ethanol has a density of 0.789 g/mL and a mass of 36.4g. Find the volume in mL

Density= 41.6mL

The density of a solution is 0.791 g/cm^3. What is the volume in cubic inches of 2.7 Ib of the solution?

95 in^3

how many centimeters are in 1.24m?

Calculate the density of a 74.5ml sample of a substance with a mass of 25.92g.

Calculate the density of a 55cm^3 sample of a substance with a mass of 13.4g

how many millimeters are in 34 meters

talia prepares a bowl of cereal with milk. when she starts to eat the cereal, she immediately spits it out because the milk has turned sour. which property change is the souring of milk an example of

chemical change

the mass of a ball is 141kg. what is its mass in ounces, given 1 oz= 28.35g

4.97x10^3 oz.

an irregular shaped metal object of mass 80.4g is placed in a granulated cylinder containing 500.5ml of water. the water level increases to 512.5ml. what is the density of this metal

6.70 g/mL

what is the mass number of an atom containing 17 protons, 18 electrons, and 20 neutrons

37

naturally occurring boron (B) is composed of 19.9% of B-10(10.013amu) and 80.1% of B-11 (11.009amu) what is the average atomic mass of boron?

10.81 amu

naturally occurring iridium (Ir) is composed of 37.30% of Ir-191(190.96amu) and 62.70% of Ir-193(192.96amu)

192.2 amu

what does a neutral atom with an atomic number greater than two consist of?

protons, neutrons, and electrons

Given the periodic table what is the relationship btwn electron negativity and atomic number for halogen group 17

Electronegativity decreases from top to bottom

given the periodic table what is the relationship btwn the atomic radius and atomic number for the period 6 elements

atomic size gradually decreases from left to right across a period

how many valence electrons are in sulfur (S)

6. elements in group 16 have 6 valence electrons

sodium has 11 electrons. which shell would contain the valence electrons of sodium (Na)

3rd shell. 1st shell holds 2 electrons(duet). next shell holds 8 electrons(duet). 3rd shell will hold the single valence electron

what is the definition of an ion

at atom or a group of atoms that carries an electrical charge

how many electrons are present in a double bond

4. double bond contains 2 bonds. each bond has 2 electrons

which of these compounds is most likely to contain an ionic bond

N2O, NaF, H2O, C6H6

NaF. an ionic compound. bond btwn a metal(Na) and nonmetal(F)

Calculate the charge of iron ion in FeCl2.

there are 2 chloride anions each with -1 charge, making a total of -2(2*-1). so the charge on the single cat ion has to be +2 to balance the negative charge.

Answer:

Fe+2

Calculate the charge on an iron ion Fe2O3.

there are 3 oxygen anions . Each with a -2 charge, making -6(3X-2=-6)

so the total charge on 2 iron atoms should be +6 i.e. the charge on each iron atom is +3(+6/2=+3).

Answer:

Fe+3

name the following compounds

Fe 2(CO3)3

KCIO4

CCI

Fe2(CO3)3= iron(111) carbonate

KCIO4= potassium perchlorate

CCI= carbon tetrachloride

Provide the formulas for the following names:

boron trifluoride

copper(11) sulfate

sodium hydroxide

boron trifluoride= BF3

copper(11) sulfate= CuSO4

sodium hydroxide= NaOH

what is the formula for ammonium carbonate

(NH4)2CO3

ammonium ion has a +1 charge, and carbonate has a -2 charge overall

how many total carbonate ions would be present in the formula for aluminum carbonate

3

aluminum has +3 charge, and carbonate has a charge of -2. 2 atoms of aluminum would have an overall charge of +6. for the compound to be electrically neutral, the anionic charge must be equal to -6. this would mean that the formula contains 2 carbonate ions.

what is the correct name for HCIO4

Perchloric acid. CIO4- polyatomic ion is present, and since the problem involves an acid, chlorate changes to chloric

term (aq) stands for aqueous.

what is the name of the following acid: HF(aq)

Hydrofluoric acid. prefix hydro is placed in front of the nonmetal with a name that ends in -ic. if HF were in a gaseous state, the name of the acid would be hydrogen fluoride. the element name is used to name the cation, and the name of the anion ends with -ide

what is the correct name for CaH2

calcium hydride. name of the metal is written as it is, and the name of the nonmetal ends with -ide

what is the charge of the ion formed by calcium (Ca)

+2. calcium is a metal in group 2. metal in group 2 lose 2 electron because this would allow them to have 8 electrons(octet) in their outermost shell

which compound would you expect to be ionic

H2S

CO2

NH3

SrCl2

SrCl2. ionic compounds have ionic bonds, ionic bonds involve a metal Sr and a nonmetal Cl

what is the correct name for a molecule of SO3

Sulfur trioxide

what is the correct name for Cl2O7

Dichlorine heptoxide

what is the correct name for a molecular unit of H2O

dihydrogen monoxide

what is the approximate bond angle btwn the atoms in a molecule with a tetrahedral electron pair geometry?

109.5' tetrahedral bond angle based on VSEPR theory. this angle is obtained when all 4 pairs of outer electrons repel each other equally.

what is the molecular geometry of CH2O

trigonal planar. 3 groups of atoms or 3 bonded groups and zero lone pairs around the central atom (carbon). VSEPR suggest that molecules with 3 groups around the central atom have trigonal planar geometry. Bond angle 120'

which atom is the most electronegative: P, Li, Cs, Cl?

Cl. Electronegativity increases as you move to the right of the periodic table and as you move down a group.

which covalent single bond is the least polar btwn: N-C, O-C, O-N, C-H

(electronegativity) H-2.1, C-2.5, N-3.0, O-3.5

C-H is a nonpolar covalent bond as the electronegativity difference for C-H bond is 0.4

which element is the least electronegative in this series: Cs, Li, P & Cl

CS electronegativity increases as you move to the right of the periodic table and as you move down a group. Cs is least electronegative.

what is the bond angle btwn 2 atoms in a trigonal planar geometry

120 degrees angle bond

how many atoms are in 14 moles of cadmium (Cd)

8.4 x 10^24 atoms Cd. avogadro's number (6.02 x 10^23) used to convert the number of moles to atoms

what is the molar mass for C6H12O6?

180.2g/mol. a single carbon atom has a mass 12g/mol. a single oxygen atom has a mass of 16g/mol, and a single hydrogen atom has a mass of 1g/mol. add all the carbons, hydrogens and oxygens in the molecular formula

what is the molar mass for Mg(OH)2

58.32 g/mol a single magnesium atom has a mass of

24.31 g/mol, and a single hydrogen atom has a mass of 1 g/mol

add the mass for magnesium, hydrogen, and oxygen

converting moles to gas volume

4.96 moles of O2. At STP, 1mol = 22.4L

unknown: volumes of O2

calculate: 4.96 mol x 22.4 L/mol=

111.1 L

converting gas volume to moles

86.5L of H2. At STP, 1 mol= 22.4 L

unknown: volume of H2

Calculate: 86.5L H2 x 1 mol/ 22.4 L H2=

3.86 mol H2

how many moles are in 40.0 grams of water H2O

1 mol of H2O= 18.1 g H2O, convert grams of H2O to moles of H2O

2.22 mol

how many formula units are in 48.0 grams of NaOH?

7.23 x 10^23. convert grams of NaOH to moles of NaOH, then convert moles of NaOH to the number of molecules using avogadro's number

Standard Temperature and Pressure (STP)

exactly 100 kPa of pressure(0.986) and 273 K (0' C)

Percent Compostion by mass

mass %= mass of element / mass of compound x 100

K2O= potassium oxide

potassium2 - 29.1 x 2= 78.2

oxygen= 16.00

78.20 + 16.00= 94.20

78.20/94.20 x 100= potassium

16/94.20 x 100= oxygen

83.01% K

16.99% O

what is the percent composition by mass for N in NH6PO4

12.18%

what is the percent composition for K in KCN?

60%

what is the mass of 0.750 moles of ZnSO4?

How many molecules are there in 0.435 moles of C6H12O6

What is the molar mass for NH4C2H3O2

What is the percent by mass for Na, P, and O in Na3PO4

What is the volume of 12.54 mol of Kr at STP

what describes molar mass

Ratio btwn mass and moles

balancing chemical equation

Al+O2 react AlO3

2Al+O2/2 = Al2O3

2(2Al+O2=Al2O3)=

4Al/4+2O/6=2Al/4O3/6

When does a chemical reaction occur?

when chemical bonds are formed or broken by atoms colliding

what coefficient needs to be placed in front of the oxygen atom 0n the products side in order to balance the following equation

KClO3->2KCl+O2

2in front of the K, you get 2KClO3->2KCl+O2. but now you have 6 O atoms on the left. to get 6 O atoms on the right, put a 3 in front of the O2.

How is an equation balanced?

by comparing the number of each type of atom in the reactant and products. for an equation to be balanced the number of atoms for each element in the reaction and the total charge must be the same for both the reactants and the products

what is the balanced product of this equation:

Pb(OH)4+H2SO4-> Pb(SO4)2+H2O

Pb(HO)4+2H2SO4->Pb(SO4)2+4H2O

Reactant: Pb=1 O=12 H=8 S=2 Products: Pb=1 O=12 H=8 S=2

if you add a 2 in front of H2SO4 = # of S atoms

if you add a 4 in front of H2O on the product side, you will have an equal # of oxygen and hydrogen atoms on both sides

What occurs in a decomposition reaction?

one substance splits into two or more simpler substances

synthesis reaction example

A + B --> AB

elements or compounds undergo a reaction and combine to form a single new substance

what describes a change in state that is associated with the loss of electrons

oxidation. the loss of electrons by an element and an increase in oxidation state creates an oxide

redox reactions (oxidation-reduction reactions)

H2+Cl2-> 2HCL

chemical reactions that transfer electrons between reactants

either increase or decrease in order to form a chemical bond with another atom.

H2 has been oxidized, and Cl2 has been reduced, making this a redox reaction

what is the correct way to interpret

P4+5O2-> P4O10

one molecule of P4

reacts with 5 molecules of O2

to produce

one molecule of P4O10

Interpret

N2+3H2-> 2NH3

one mole of N2 reacts with

3 moles of H2

to produce

two moles of NH3

what is the oxidizing agent in

2Na+2H2O-> 2NaOH+H2

H2O

an oxidizing agent is a substance that loses oxygen or gains hydrogen. both side of the equation lose oxygen

chemical equation H2O2(aq)-> H2O(l)+O2(g)

what is the role of H2O2?

Reactant

a compound that is on the right side and breaks down is called a reactant.

which 2 elements are diatomic

Carbon, Nitrogen, Fluorine, Sodium

Nitrogen: composed of two atoms, need for diatomic molecules

Fluorine: naturally occurring diatomic molecules have two atoms

what is the product of a synthesis reaction btwn potassium and chloride

KCl

what is true about moles

a mole ratio relates to the amount of any two substances in a chemical reaction. a mole ratio is a conversion factor btwn compounds in a chemical reaction. it relates the amounts in moles of any two substances in a chemical reaction.

what common mass used in laboratory setting

Grams. Grams and kilograms are part of the metric system and reflect the quantity of matter within a sample.

what mass of hydrogen peroxide must decompose to produce 48.64g of water?

2H2O2-> O2+ 2H2O

Given 48.64g H2O

Find g H2O2

g H2O -> mol H2O -> mol H2O2 -> g H2O2

1. molar mass of H2O 2. mol: mol #. molar mass of H2O2

48.6g H2O (1 mol H2O/18.02g H2O) (2mol H2O2/2mol H2O) (34.02g H2O2/ 1mol H2O2)=

48.64x1x2x34.03/18.02x2x1= 91.83g H2O2

How many molecules of carbon dioxide are required to react with 174g of carbon monoxide?

2Co+ O2 -> 2CO2

1. g CO -> 2. mol CO2 -> molecules CO2

1. molar mass of CO 2. mol:mol 3. Avogadro's number

174g CO (1mol CO/28.01g CO) (2 mol CO2/ 2mol CO) (6.022x 10^23 molecules /1 mol CO2)=

3.74x10^24 molecules CO2

which would be investigated in reaction stoichiometry

the mass of potassium required to produce an unknown mass of potassium chloride

given the balance equation, how many moles of water H2O are produced by the complete reaction of 4.0 moles C2H6?

2CH6+ 7O2-> 6H2O+ 4CO2

given the balanced equation how many grams of water (H2O=18.015g/mol) are produced by the complete reaction of 5.22 moles O2

2C2H6+ 7O2-> 6H2O + 4CO2

given the balanced equation how many grams of hydrogen gas

(H2= 2.016 g/mol) are produced by the complete reaction of 489.2 g of hydrochloric acid (HCL= 36.458 g/mol)

2Na (s) + 2HCl (aq) -> 2NaCl (aq) + H2 (g)