Chem 2
Arrange the necessary steps in order for finding the molecular formula of an unknown compound from mass percent data. Place the first step at the top of the list.
-Assume that the sample contains 100.0 g of compound and express each mass percent as a mass in grams - Convert the mass of each element to moles of each element - Derive the empirical formula looking for the simplest whole number ratio of moles - Divide the molar mass of the compound by the mass of the empirical formula in order to find a multiple that is an integer - Subscript of the empirical formula by the integer multiple
The formula mass of K2CO3 is equal to _____.
138.21 amu
The molecular formula of a compound having an empirical formula NH2 (ℳ = 32.05 g/mol) is N ____________ H ___________
2, 4
The correct formula for the compound dichlorine pentoxide is Cl ______ O ________ . Enter your answer in the correct format.
2,5
Which of the following provides the correct mathematical operation to calculate the number of molecules in 2.0 mol of CH4?
2.0mol X 6.022 X 10^23 molecules/mol
The covalently bonded species shown has _____ bonding pair(s) of electrons and _____ lone pair(s). (H3 N)
3,1
Calculate the correct number of moles AND formula units in 7.3 x 10-3 g of CaSO4. Avogadro's number is 6.022 × 1023.
3.2 × 1019 formula units of CaSO4 5.4 × 10-5 moles of CaSO4
What is the mass percent of oxygen in aluminum oxide (Al2O3)?
47.08%
Which of the following equations will give the correct formula mass of the compound Fe(ClO4)2?
55.85 + 2(35.45) + 8(16.00)
What is the total number of electrons shared between two atoms in a triple bond?
6
How many grams of KMnO4 correspond to 3.13 × 1022 formula units of KMnO4? Avogadro's number is 6.022 × 1023.
8.21g of KMnO4
Which of the following statements about Lewis structures are correct?
A Lewis structure shows the number of covalent bonds between bonded atoms. A covalent bond is represented as a line or as dots between atoms. Lone pair electrons are represented as pairs of dots.
Select the statements that correctly describe naming an oxoanion. Select all that apply
An oxoanion containing two fewer oxygen atoms than the -ate ion is called the hypo...ite ion. An oxoanion containing one more oxygen atom than the -ate ion will have the prefix per- added.
Select all the statements that correctly describe multiple bonds.
Bond strength increases with the number of electron pairs shared between two atoms. A multiple bond arises when two atoms share two or more electron pairs. Carbon frequently forms multiple bonds.
Order the covalent bonds shown by length, beginning with the shortest at the top of the list.
C,A,B
A particular hydrocarbon (a compound consisting only of C and H) contains 14.4% H by mass. If the molar mass of the compound is 85. ± 2 g/mol, what is the molecular formula?
C6H12
A compound has the empirical formula CH2O. What are the possible options for the molecular formula of this compound? Select all that apply.
C6H12O6 CH2O C2H4O2
Match each compound with the correct mass % of hydrogen (H).
C6H6: 7.7% CH3OH: 12.6% CH2O: 6.71%
Correctly associate each molar mass with its compound.
CCl4, 153.8 CH2O, 30.03 SF6, 146.1 KrF2, 121.8
Many polyatomic ions are oxoanions, containing a nonmetal bonded to one or more oxygen atoms. If ClO3- has the name chlorate, match each of the other oxoanions in the same family to its correct name.
ClO4 perchlorate ClO2 chlorite ClO- hypochlorite
True or false: All of the electrons in a many-electron atom can participate in covalent bonding.
False
Which of the following compounds has the largest molar mass?
H2SO4
Select all the polyprotic acids.
H2SO4 H3PO4
Which of the following acids is named correctly as an acid?
HBR: hydrobromic acid
A ___________ structure represents the covalent bonds and nonbonding electrons for a given chemical compound.
Lewis
Which of the following formulas for ionic compounds are written correctly? Select all that apply.
Mg3(PO4)2 ; CaCO3 ; NaNO3
Some covalent compounds are so common that they are named using "common" or "trivial" names instead of systematic names. Match each of the following compounds with its correct name.
NH3 ammonia H2O water PH3 phosphine
Match each oxoanion with its correct name.
NO3- nitrate NO2- nitrite ClO3- chlorate ClO- hypochlorite
Match each of the following polyatomic ions with its correct name.
OH- hydroxide NO2- nitrite NO3- nitrate PO 3 4- phosphate NH4+ - ammonium
Match each oxoanion with its correct name.
PO43-, phosphate PO33-, phosphite BrO3- ,bromate BrO2- bromite
Match the name for each polyatomic ion with its correct formula.
Sulfate- SO4^2- Sulfite- SO3^2- Permanganate- MnO4 Carbonate- CO3^2
Greek numerical prefixes are used to indicate the number of atoms of a particular element present in a molecular compound. Four atoms of the same element will be named with the prefix ________ , while the prefix ________ is used to indicate two atoms of the same element.
Tetra, Di
Which of the following statements correctly describe the rules for naming oxoacids? Select all that apply.
The acid derived from the bromate anion would be called bromic acid. The acid derived from the chlorite anion would be called chlorous acid. The names of oxoacids are related to the names of the oxoanions from which they are derived.
Which of the following statements correctly describe how to calculate a molecular or formula mass for a compound? (Recall that a subscript of "1" is assumed)
The atomic mass of a cation or anion is the same as the mass of the neutral element. The formula/molecular mass is derived from the sum of the masses of all atoms of the component elements. In a formula such as Ca(NO3)2, all subscripts of atoms in parentheses must be multiplied by 2.
Which of the following options correctly describe a polyatomic ion? Select all that apply.
The charge on a polyatomic ion belongs to the whole unit. The atoms of a polyatomic ion are held together by covalent bonds.
Select all the pieces of information that are necessary to calculate the mass % of an element in a given compound.
The formula of the compound The molecular or formula mass of the compound The number of atoms of the element in a molecule or formula unit of the compound
Which of the following statements are part of the proper calculation of the mass % of O in acetic acid (CH3COOH)? Select all that apply.
The molar mass of acetic acid is 60.05 g/mol. The mass of oxygen atoms in a mole of acetic acid is 32.00 g. % O = 53.29%
Which of the following is NOT involved in determining the empirical formula of a compound from mass percent data?
The molar mass of the compound
Which of the following statements correctly describe how to name acids? Select all that apply. The name of a binary acid contains the nonmetal root with the suffix -ic. Binary acids are named using the prefix hydro-. The name of a binary acid begins with the name of the nonmetal it contains. If the compound HCl is named as an acid, it would be called hydrogen chloride.
The name of a binary acid contains the nonmetal root with the suffix -ic. Binary acids are named using the prefix hydro-.
Which of the following statements correctly describe molar mass? Select all that apply.
The periodic table can be used to calculate the molar mass of any substance. The molar mass is the mass in grams per mole of the substance.
Which of the following statements correctly describe how to name a binary molecular compound? Select all that apply.
The second element is named with its root and the suffix -ide. A Greek numerical prefix is used to indicate the number of atoms of each element in the compound. The name of the first element remains unchanged, except for the addition of a prefix where appropriate.
Give the common name for each of the following molecular compounds. NH3 _______ is and H2O is ______________ .
ammonia, water
When naming a molecular compound, the number of _________ of each element is indicated by a Greek numerical prefix. The first element in the name is numbered only when more than ______ atom of that element is present.
atoms, one
A pair of electrons shared between two atoms in a covalent bond is called a shared or electron pair, whereas an outer-level electron pair that is not involved in bonding is called an unshared or pair.
bonding lone
The BrO3- ion is named bromate. What is the name of the oxoacid with the formula HBrO3?
bromic acid
Match each anion name on the left with the name of its corresponding acid on the right.
chloride, hydrochloric acid chlorite, cholorous acid perchlorate, perchloric phosphate, phosphoric acid phosphite, phosphorous
Match each Greek numerical prefix with the correct number of atoms/entities it indicates.
di 2 penta 5 hexa 6 mono 1 hepta 7
Formula and molecular masses are calculated using the chemical _________ of the relevant compound, and the atomic masses obtained from the ____________ table. The _________ of the atomic masses in the correct proportions gives the formula or molecular mass of the compound.
formula; periodic; sum
A carbon-carbon double bond is ______ than a carbon-carbon triple bond, and ______ than a carbon-carbon single bond.
longer shorter
Which one of the following options gives the correct procedure to calculate the number of moles of a substance given the mass of a sample?
mass / molar mass
The _________ ___________ of a substance is the mass per mole of a substance, in units of g/mol.
molar, mass
The _____ formula of a compound is an integer multiple of the _____ formula.
molecular; empirical
Which one of the following options gives the correct procedure to calculate the mass of a substance given the number of moles?
moles × molar mass
An acid that has only one ionizable proton is termed ________ , whereas an acid with two or more ionizable protons is termed ____________.
monoprotic, polyprotic
The oxoacid of the nitrate ion is called _____ while that of the nitrite ion is called ______.
nitric acid; nitrous acid
Which of the following is the correct name for the molecular compound NO2?
nitrogen dioxide
Which of the following provides the correct mathematical operation to convert the number of atoms of a sample to the number of moles?
number of atoms / Avogadro
The rule states that when atoms bond they may lose, gain, or electrons in order to attain an outer level containing eight electrons.
octet; share
A unit that contains two or more atoms covalently bonded together but that has an overall charge is called a(n) _____ ion. Many _____ compounds contain such units.
polytomic, ionic
What is the correct systematic name for the compound Na2CO3?
sodium carbonate
Between the same two atoms, the strongest covalent bond is the _____ bond and the weakest is the _____ bond.
triple; single
In a many-electron atom, only the electrons at the ______ level will participate in covalent bonding.
valence
Atoms bond in order to attain a full level or shell of electrons. Elements in period 2 seek a total of such electrons while period 1 elements such as hydrogen seek a total of .
valence; 8, 2