Math of Chem
What is the chemical formula for ammonium sulfide?
(NH4)2S
Which quantity of O2 contains exactly 3.01 × 10^23 molecules?
0.500 mole
Which represents the greatest mass of chlorine?
1 mole of chlorine
Which quantity of particles is correctly represented by the formula H2SO4?
1.0 mole of molecules
Which sample contains a total of 9.0 × 10^23 atoms?
1.5 moles of Cu
How many molecules are in 0.25 mole of O2?
1.5 × 10^23
CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O() + CO2(g) What is the total number of moles of CO2 formed when 20. moles of HCl is completely consumed?
10. mol
What is the gram formula mass of Na2CO3 • 10H2O?
106 g
What is the gram-formula mass of (NH4)3PO4?
149 g/mol
What is the percent composition by mass of aluminum in Al2(SO4)3 (gram-formula mass = 342 grams/mole)?
15.8%
According to the reaction H2 + Cl2 → 2 HCl, the production of 2.0 moles of HCl would require 70. grams of Cl2 and
2.0 g of H2
What is the approximate percent composition by mass of CaBr2 (formula mass = 200)?
20% calcium and 80% bromine
A 10.0 gram sample of a hydrate was heated until all the water of hydration was driven off. The mass of anhydrous product remaining was 8.00 grams. What is the percent of water in the hydrate?
20.0%
How many grams of oxygen can be recovered from the decomposition of 55 grams of MgO?
22g
What is the gram-formula mass of Fe(NO3)3?
242 g/mol
A 20. gram sample of a hydrate is heated until all the water of hydration is driven off. The mass of the anhydrous compound remaining is 15 grams. What is the percent by mass of water in the hydrate?
25%
What is the percent composition by mass of nitrogen in (NH4)2CO3 (gram-formula mass = 96.0 g/mol)?
29.2%
Which balanced equation represents a chemical change?
2H2O() + energy → 2H2(g) + O2(g)
What is the total number of different elements present in NH4NO3
3
What is the total number of molecules in a 0.5-mole sample of He gas?
3 × 10^23
The percent by mass of hydrogen in NH3 is equal to
3/17 x 100
What is the gram formula mass of Ca3(PO4)2?
310 g
N2 + 3 H2 → 2 NH3 How many grams of ammonia are produced when 1.0 mole of nitrogen reacts?
34
What is the percent composition by mass of nitrogen in NH4NO3 (gram-formula mass = 80.0 grams/mole)?
35.0%
A laboratory experiment was performed to determine the percent by mass of water in a hydrate. The accepted value is 36.0% water. Which observed value has an error of 5.00%?
37.8% water
Ca + 2 H2O → Ca(OH)2 + H2 How many moles of H2O are needed to exactly react with 2.0 moles of Ca?
4.0
What is the mass of 1.5 moles of CO2?
44g
What is the number of moles of CO2 in a 220.-gram sample of CO2 (gram-formula mass = 44 g/mol)?
5.0 mol
What is the approximate total number of atoms in 1.0 mole of lithium?
6.0 × 10^23
What is the total number of atoms contained in a 1.00-mole sample of helium?
6.02 × 10^23 atoms
A student determined that the percent of H2O in a hydrate was 39.0%. The percent of H2O in this hydrate is 36.0% according to an accepted chemistry reference. What is the student's percent of error?
8.3%
A 1.0-mole sample of krypton gas has a mass of
84 g
A hydrate is a compound that includes water molecules within its crystal structure. During an experiment to determine the percent by mass of water in a hydrated crystal, a student found the mass of the hydrated crystal to be 4.10 grams. After heating to constant mass, the mass was 3.70 grams. What is the percent by mass of water in this crystal?
9.8%
What is the chemical formula of Aluminum Hydroxide?
Al(OH)3
Atoms of which set of elements all exhibit the same oxidation state?
Be, Ca, Sr
Which formula represents a binary compound?
C3H8
4Fe + 3O2 2X
Fe2O3
What is the formula for iron(II) oxide?
FeO
A metal, M, forms an oxide compound with the general formula M2O. In which group on the Periodic Table could metal M be found?
Group 16
What is the correct formula of potassium hydride?
KH
If M represents an element in Group 2, the formula of its chloride would be
MCl2
In the formula XSO4, the symbol X could represent the element
Mg
What is the chemical formula for sodium oxalate?
Na2C2O4
What is the chemical formula for sodium sulfate?
Na2SO4
The chemical formula for nickel (II) bromide is
NiBr2
Which equation shows a conservation of mass?
PCl5 → PCl3 + Cl2
What is the chemical formula for lead(IV) oxide?
PbO2
What is the name of TiO2?
Titanium (IV) Oxide
What is a hydrate?
a salt crystal with water as part of its molecular formula
If an equation is balanced properly, both sides of the equation must have the same number of
atoms
In which compound is the ratio of metal ions to nonmetal ions 1 to 2?
calcium bromide
A balanced equation representing a chemical reaction can be written using
chemical formulas and coefficients
Every water molecule has two hydrogen atoms bonded to one oxygen atom. This fact supports the concept that elements in a compound are
chemically combined in a fixed proportion
The correct name for the compound NaClO3 is sodium
chlorate
What is the correct name for the compound with the formula CrPO4?
chromium (III) phosphate
sodium chlorate sodium chloride + oxygen
decomposition
Which list includes three types of chemical reactions?
decomposition, single replacement, and double replacement
2 SO2(g) + O2(g) ↔ 2 SO3(g)
double replacement
NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)
double replacement reaction
According to the Periodic Table, which element has more than one positive oxidation state?
iron
What is the correct name of Fe2O3?
iron (III) oxide
What is the IUPAC name for the compound FeS?
iron(II) sulfide
Atoms of metals tend to
lose electrons and form positive ions
What is the name for NaClO3?
sodium chlorate
What is the chemical name for Na2SO3?
sodium sulfite
H2(g) + I2(g) ↔ 2 HI(g)
synthesis
Given a balanced chemical equation it is always possible to determine
the relative number of moles taking part in the reaction
The formula mass of a compound is the
the sum of the atomic masses of its atoms
Which is true regarding the percent composition by mass of water?
there is a higher percentage of oxygen than hydrogen
What is the IUPAC name for the compound ZnO?
zinc oxide
