Abeka 11th grade Chemistry Test 2

What is the value of Avogadro's number?

6.022 x 10^23

A molecule of the sugar fructose contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. What is its empirical formula?

CH(subscript 2)O

Which of the following mole ratios CANNOT be derived from the equation 2 C(subscript 7)H(subscript 8)(g) + 9 O(subscript 2)(g)----> 7 CO(subscript 2) (g) + 4 H(subscript 2)O(g)?

4 mol C(subscript 7)H(subscript 8) : 2 mol H(subscript 2)O

If the empirical formula of a substance is known, what additional information is needed to calculate the molecular formula?

molar mass

What is the formula of nitrogen dioxide?

NO(subscript 2)

What is the formula of copper(I) hydroxide?

CuOH

what is the formula of calcium carbonate?

CaCO(subscript 3)

NO 3 -

nitrate ion

NH 4 +

ammonium ion

SO 4 2-

sulfate ion

Fe 2 +

iron(II) ion

phosphate ion

3-

chloride ion

1-

lead(II) ion

2+

hydrogen ion

1+

(NH 4) 2 SO 4

ammonium sulfate

SF 6

sulfur hexafluoride

NaOH

sodium hydroxide

CO 2

carbon dioxide

Fe (NO 3) 2

iron(II) nitrate

2 Ag 2 O (s) ---> 4 Ag(s) + O 2 (g)

decomposition reaction

BaCL 2(aq) + K 2 CrO 4(aq)---> 2 BaCrO 4(aq) + 2 KCl(s)

double-displacement reaction

Ag(s)
+ NaCl(aq)--->AgCl(s) + Na(s)

single-displacement reaction

NH 3(g) + HCl(g)--->NH 4 Cl(s)

combination reaction

H 2 O(g)---> 2 H 2(g) + O 2(g)

decomposition reaction

What unit of measure is equivalent to
Avogadro's number of objects?

mole

What is a set of symbols that tells how many of each type of atom are found in a molecule?

molecular formula

What is the sum of atomic masses of all the atoms in a molecule?

molecular mass

N 2 H 4 (hydrazine) is sometimes used as rocket fuel because it reacts readily with oxygen-containing compounds to produce large amounts of hot gas; one such reaction is 2 N 2 H 4 (l) + N 2 O 4 (l)---> 3 N 2(g) + 4 H 2 O(g). If 3 mol N 2)(g) + 4 H 4 and 4 mol N 2 O 4 are available at the beginning of this reaction, which substance will be the limiting reactant?

N 2 H 4 (hydrazine)

Ca(s) + 2 H(subscript 2)O(l)---> Ca(OH)(subscript 2) (aq) + H(subscript 2) (g)

Ca(s) + 2 H(subscript 2)O(l)---> Ca(OH)(subscript 2) (aq) + H(subscript 2) (g)

KClO(subscript 3)(s)---> KCl(s) + O(subscript 2)(g)

2 KClO(subscript 3)(s)---> 2 KCl(s) + 3 O(subscript 2)(g)

Sb(subscript 2)S(subscript 3)(s) + O(subscript 2(g)---> Sb(subscript 2)O(subscript 3)(s) + SO(subscript 2(g)

2 Sb(subscript 2)S(subscript 3)(s) + 9 O(subscript 2(g)--->2 Sb(subscript 2)O(subscript 3)(s) + 6 SO(subscript 2(g)

Find the molecular mass of NO(subscript 2)
(You might need the periodic table.)

46.01 u

Fins the molar mass of AgNO(subscript 3)
(You might need the periodic table.)

169.9 g/mol

Consider the reaction 2 Al(s) + Fe(subscript 2)O(subscript 3)O(s)--->2 Fe(l) + Al(subscript 2)O(subscript 3)(s). If 60.0 g of Al is reacted with excess Fe(subscript 2)O(subscript 3), determine the amount (in moles) and mass (in grams) of Al(subscript 2)O(subscript 3) produced. {M[subscript Al(subscript 2)O(subscript 3)]= 101.96 g/mol}

1.11 mol; 113 g

the reaction 2 Al(s) + Fe(subscript 2)O(subscript 3)O(s)--->2 Fe(l) + Al(subscript 2)O(subscript 3)(s). If 60.0 g of Al is reacted with excess Fe(subscript 2)O(subscript 3), determine the amount (in moles) and mass (in grams) of Al(subscript 2)O(subscript 3) produced. {M[subscript Al(subscript 2)O(subscript 3)]= 101.96 g/mol}






















1.11 mol; 113 g























A 75.00 g sample of a substance is analyzed is found consist of 32.73 g phosphorus and 42.27 g oxygen. Calculate the percent composition of this substance.

43.64% P; 56.36% O

The mineral cuprite consists of 88.8% Cu and 11.2% O by mass; determine the empirical formula of cuprite.

Cu(subscript 2)O

In the presence of sulfuric acid, one molecule of ethanol [C(subscript 2)H(subscript 6)O] can react to form one molecule each of water and another product:
C(subscript 2)H(subscript 6)O--->H(subscript 2)O +?
Using the law of conservation of mass, describe a technique a chemist could use to predict the formula of the unknown product; then use the technique you described to predict the formula of the unknown product.

*According to the law of conservation of mass, the sum of the masses of the products is always equal to the sum of the masses of the reactants. Since atoms do not change from one type of atom that the reactants did.

*In this reaction, the total number of each type of atom in the products (water and the unknown) must equal the number of each type of atom in the reactant (ethanol), which is known. the number of each type of atom in the unknown (and thus the formula of the unknown) can be determined by subtracting the number of each type of atom in the known product from the number of each type of atom in the reactant.

*The reactants contain 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom, and the known product contains 2 hydrogen atoms and 1 oxygen atom. the unknown product must contain 2 carbon atoms, 6-2=4 hydrogen atoms, and 1-1=0 oxygen atoms.

*The Formula of the unknown product is C 2 H 4 [or H 4 C 2].