Chemistry quizzes
What is the charge on each chlorine in an ionic compound composed of calcium and chlorine?
-1
endothermic vs exothermic
...
How many nanometers are in a meter?
1 x 109
There are five different objects with the diameters shown below. Which of these objects cannot be seen with the naked eye? 1.0 km 1.0 mm 1.0 μm 1.0 dm 1.0 cm
1.0 μm
Carbon-11 has a half-life of 20 minutes. Which of the following equations is used to calculate the amount of carbon-11 remaining after one hour if the starting material a 100-mg sample?
100 mg × 1/2 × 1/2 × 1/2
What is the total number of valence electrons in the chloroethylene molecule (C2H3Cl)?
18
The balanced chemical equation for the combustion of butane (C4H10) is given below. How many grams of O2 are needed to completely react with 5.0 g of butane in a butane lighter? 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
18 g
Calculate the molecular mass of aspirin, C9H8O4.
180 amu
Calculate the mass (in grams) of a gold cube with sides of 0.85 in. The density of gold is 19.32 g/cm3.
194.93 g
How many moles of carbon are in 27.1 g of carbon?
2.26 moles
A copper pipe with a mass of 1200 g and a specific heat of 0.093 cal/g°C absorbs 252 calories of heat. By how many degrees does the temperature of the pipe change?
2.3°C
How many copper atoms are in 0.5 moles of copper?
3.01 × 10^23
One serving of animal crackers (30 g) contains 4.5 g of fat, 22 g of carbohydrates, and 2 g of proteins. What would you use to determine the number of calories in one serving of animal crackers?
4.5 g × 9 Cal/g + 22 g × 4 Cal/g + 2 g × 4 Cal/g
How many nonbonding electrons are in the chloroethylene molecule (C2H3Cl)?
6
how do formula mass and molecular mass differ?
A formula mass is the mass of one unit of an ionic lattice, whereas molecular mass is the mass of one molecule.
Which of the following statements describes reaction rate? You Answered Reaction rate is how fast a reaction proceeds. Reaction rate is the quantity of reactants consumed over time. Reaction rate is the quantity of products formed over time. Reaction rate is determined, in part, by activation energy. All of the above
All of the above
During catabolism of food, heat is released. Where does this energy go? It is turned into heat energy. It is used in movement. It is used to drive additional chemical reactions. It is transferred to ATP. All of the above are possible.
All of the above are possible
The following reaction is a reversible reaction. Which of the following statements best describes what it means for this reaction to be reversible? HCOOH + HOCH3 HCOOCH3 + H2O
Forward and reverse reactions proceed at the same rate.
Below are four molecules and compounds. Choose the statement below that best describes these four. CH2O (I) Ti2O3 (II) MgO (III) H2O (IV)
II and III are ionic, whereas I and IV are covalent.
How does increasing the temperature of a reaction affect the rate?
It speeds it up by increasing the kinetic energy of the molecules.
A compound contains magnesium and phosphate. What is the formula unit of this compound?
Mg3(PO4)2
Magnesium chloride is sometimes administered orally to suppress premature labor. Which of the following is a valid ionic formula for magnesium chloride?
MgCl2
why do we use moles when measuring quantities of atoms and molecules?
Moles are used because atoms and molecules are too small to measure singly.
The reaction of water with ammonia is shown below. What will happen if ammonium is added to the solution when it is at equilibrium? NH3 + H2O +NH4 + -OHammonia water ammonium hydroxide
The equilibrium will shift to the left.
In an exothermic reaction, the reactants are higher in energy than the products. What is the meaning of this difference in energy?
The products are more stable than the reactants.
Nonmetals typically ______ and metals typically ______.
accept electrons; donate electrons
Which of the following do you expect would increase the rate of a reaction? adding a catalyst decreasing temperature decreasing concentration removing product as it is formed All of the above
adding a catalyst
when bonds break, energy is
always absorbed
An ion that has more electrons than protons is a(n) ________.
anion
Which of the following transformations is a chemical reaction? dry ice changing from a solid to a gas water boiling All of the above burning wood condensation on the outside of a water glass
burning wood
Which of the following do you expect would decrease the rate of a reaction? adding a catalyst increasing temperature increasing concentration decreasing concentration All of the above
decreasing concentration
__________ are the subatomic particles that have the smallest mass
electrons
What are biological catalysts called?
enzymes
Combustion reactions are ___________ because products of the reaction are _________ in potential energy than the reactants.
exothermic, lower
___________ are neutral
neutrons
An important part of writing a formula unit for an ionic compound is to make sure that
the charges of the ions add up to zero.
