PS test #5

Which of the following states the law of conservation of mass?

11 &22

Which coefficients correctly balance the formula (skeleton) equation CaO + H2O → Ca(OH)2? 55% 1819 35% test err 1718

111

The number of oxygen atoms in a molecule of Mg(OH)2 is

2

When the equation KClO(s) KCl(s) + O(g) is balanced, the coefficient of KClO3 is

2

Which of the following shows the law of conservation of mass? 40% 1819

24 g of Mg burn in 32 g O2 to produce 56 g of MgO.

How many oxygen atoms are present in this molecule? 7Na3PO4

28

Which of the following equations represents a decomposition reaction?Select one:

2HgO (s) → 2Hg(l) + 2 O2(g

Which example shows where a coefficient is used correctly to balance the equation? 55% 1819

2K + Cl2 → 2KCl2

In the chemical equation, 2HCl + Ca(OH)2 CaCl2 + 2H2O the number of molecules of reactants is

3

Balance the following equation to demonstrate the conservation of atoms in a reaction. Choose the answer which provides the correct coefficients for each reactant and product. 40% test err 1819 _____ Fe + _____ O2 _____ Fe2O3

432

Which of the following chemical reactions illustrates a combustion reaction? 30% final err 1819

4H2 + 2O2 → 2H2O

Which of the following chemical reactions illustrates a synthesis or addition reaction?

4H2 + 2S2 → 2H2S

How many carbon atoms are in this glucose molecule? C6H12O6

6

How many oxygen atoms are present in 2Fe2O3

6

The number of oxygen atoms in a molecule of Mg(NO3)2 is 50% test err 1718

6

In the chemical equation, 2HCl + Ca(OH)2 CaCl2 + 2H2O the number of atoms of reactants is

9

The general equation representing a double replacement reaction is:

AB + CD ---AD + CB

The general equation representing an decomposition reaction is:

AB ---A + B

The general equation representing a single replacement reaction is:

AX + B---BX + A

Classify the following reaction: Cu(NO3)2 + 2NaOH Cu(OH)2 + 2NaNO3

Double-displacement

How do you know that a chemical equation is balanced?

Equal numbers of atoms by type at the start and the end

Which of the following states the law of conservation of mass?

Mass cannot be created or destroyed in a chemical reaction.

Hydrochloric acid, HCl, is added to solid NaOH. After the reaction is complete, NaCl dissolved in water remains. What are the products of this chemical reaction?

NaCl and H2O

Classify the following reaction: 40% test err 17183CuSO4 + 2Al Al2(SO4)3 + 3Cu

Single-displacement

Which of the following is NOT always true about a synthesis or addition reaction?

There is only one reactant

If you designed your own experiment to prove the law of conservation of mass, what conditions would be required?

You must find the mass of the reactants before the reaction, find the mass of the products after the reaction, AND perform the reaction in a closed system.

In a single-displacement reaction

a more reactive element can replace a less reactive element.

Which of the following is PROOF that a chemical reaction has taken place?

a new substance with different properties is formed

When a chemical change occurs:

a.the law of conservation of mass is always obeyed.b.the chemical properties of new substances are different from the ones you started with.c.bonds are broken and reformed so atoms are rearranged

Why does of conservation of mass dictate that chemical equations be balanced? 40% test err 1617

because atoms are never gained or lost in a chemical reaction

Of the following, which most likely involves a chemical reaction?

boiling water turns a fresh egg into a hard boiled egg

When a physical change occurs

bonds are neither broken nor reformed so atoms are not rearranged. (11)

In the equation: Pb(NO)3(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq) in what form does PbI2 appear? 30% test err 1617

both solid and precipitate

A solid that forms and is insoluble is evidence of a: 45% test err 1819

chemical reaction

Which of the following describes chlorophyll breaking down into new substances?

chemical reaction

What is the whole number placed in front of a molecular formula in a chemical equation called? It tells you how many molecules or particles, not atoms. ( 5FeO ) 50% 1819

coefficient

The general name for chemical reactions combining oxygen with other reactants to release large amounts of energy in the form of heat and light is:

combustion

Classify the following reaction: Cu(OH)2 CuO + H2O

decomposition

In the reaction, 2H2O2(l) 2H2O(l) + O2(g), the phase of matter of O2 (g) is: 45% test err 1819

gas

In the reaction, 2H2(g) + O2(g) 2H2O(l), the reactant(s) is/are 35% test err 1819

h2 & o2

In the reaction, 2H2(g) + O2(g) 2H2O(l), the product(s) is/are 35% test err 1819

h2o

Which of the following is NOT an example of a chemical reaction?

ice melting

Which of the following is an example of a chemical reaction?

leaves changing colors in the fall

In the reaction, 2H2O2(l) 2H2O(l) + O2(g), the phase of matter of H2O(l) is: 45% test err 1819

liquid

Which of the following is an example of a diatomic molecule?

o2

If a chemical symbol in a chemical formula has no subscript, such as 2NO, it means

only one atom of the element is in the molecule

Evidence for a chemical change includes all of the following EXCEPT: 35% test err 1718

phase or state change

When you eat an apple, the process of digestion involves:

physical and chemical change

A solid that forms and is insoluble in the reaction mixture is called a:

precipitate

A general name for ALL substances created in a chemical reaction is:

product

A general name for ALL initial substances in a chemical reaction is:

reactant

hat is a whole number in a chemical formula, such as NO2, indicating the number of atoms in a molecule called?

subscript

Evidence for a chemical change includes all of the following EXCEPT:

substance dissolving

The principle of conservation of atoms is satisfied in a chemical equation when:

the reactant side has the same number of each type of atom as the product side.