HighFour Chemistry
Category C: Grades 9 – 10
Round 10
Tuesday, June 14, 2016
The use of calculator is required.
Question #1
Given the following chemical reaction, determine the number of moles of
sulfuric acid to balance the chemical equation:
Al
+
H2SO4
→
Al2(SO4)3
+
H2
Question #2
Analysis of a metal chloride XCl3 shows that it contains 67.2 percent Cl by
mass. Identify the element by calculating the molar mass of X. Write the
chemical name of the element.
Question #3
Name the only country that is named after an element.
Question #4
Calculate the number of neutrons of
Question #5
The natural abundances of elements in the human body, expressed as
percent by mass, are: oxygen (O), 65 percent; carbon (C), 18 percent;
hydrogen (H), 10 percent; nitrogen (N), 3 percent; calcium (Ca), 1.6 percent;
phosphorus (P), 1.2 percent; all other elements, 1.2 percent. Calculate the
mass in grams of calcium in the body of a 62-kg person.
.
HighFour Chemistry
Category C: Grades 9 – 10
Round 10
Tuesday, June 14, 2016
The use of calculator is required.
Question #6
What volume (in mL) of 0.500 M HCl solution is needed to neutralize
completely 10.0 mL of a 0.300 M NaOH solution?
Question #7
Peroxyacylnitrate (PAN) is one of the components of smog. It is a
compound of C, H, N, and O. Determine the number of atoms of oxygen in
the empirical formula from the following percent composition by mass:
19.8 percent C, 2.50 percent H, 11.60 percent N.
Question #8
Name the following compound: Ag2CO3.
Question #9
Some compounds are better known by their common
names than by their systematic chemical names. Give the
chemical name of milk of magnesia.
Question #10
Calculate the molar mass of Mg3N2.
HighFour Chemistry
Category C: Grades 9 – 10
Round 10
Tuesday, June 14, 2016
The use of calculator is required.
Question #11
What do you call the
phenomenon wherein heat is
trapped near the Earth’s surface
by gases in the atmosphere,
particularly carbon dioxide?
Question #12
Consider the reaction
MnO2
+
4HCl
→
MnCl2
+
Cl2
+
2H2O
If 0.86 mole of MnO2 and 48.2 grams of HCl react, how many grams of Cl2
will be produced?
Question #13
As part of their quality monitoring, manufacturers of carbonated drinks
measure the glucose content of the products. Glucose has the formula
C6H12O6. What is the empirical formula of glucose?
Question #14
An inflated balloon has a volume of 0.55 L at sea level (1.0 atm) and is
allowed to rise to a height of 6.5 km, where the pressure is about 0.40 atm.
Assuming that the temperature remains constant, what is the final volume
(in liters) of the balloon?
Question #15
A mixture of gases contains 4.46 moles of neon (Ne), 0.74 mole of argon
(Ar), and 2.15 moles of xenon (Xe). Calculate the partial pressure (in atm) of
neon if the total pressure is 2.00 atm at a certain temperature.
HighFour Chemistry
Category C: Grades 9 – 10
Round 10
Tuesday, June 14, 2016
The use of calculator is required.
Question #16
When a solution of magnesium nitrate
reacts with an aqueous solution of
sodium hydroxide, two products are
formed and one of them is sodium
nitrate. Write the chemical name of the
other product formed.
Question #17
The strength of a covalent bond is measured in terms of _______________.
It can also be used to estimate the enthalpy of reactions. Fill in the blank
with the correct answer.
Question #18
Determine how many grams of sodium carbonate (Na2CO3) would be
needed to make 2.50 x 102 mL of a 0.100 M solution.
Question #19
Argon is an inert gas used in lightbulbs to retard the
vaporization of the filament. A certain lightbulb
containing argon at 1.20 atm and 18°C is heated to
85°C at constant volume. Calculate its final pressure (in
atm).
Question #20
Chlorine is used to disinfect swimming pools. The accepted concentration
for this purpose is 1 ppm chlorine, or 1 gram of chlorine per million grams
of water. Calculate the volume of chlorine solution (in milliliters) a
homeowner should add to her swimming pool if the solution contains 6.0%
chlorine by mass and there are 2.0 x 104 gallons of water in the pool. (Note:
1 gal = 3.79 L; density of water and chlorine solution = 1.0 g/mL).