Chapter 19 Review
How would you write the metal silver in a chemical equation? Why?
Ag(s) because silver is a solid at room temperature.
What is the correct formula for aluminum oxide?
Al2O3
Why is an unbalanced chemical equation invalid?
An unbalanced chemical equation is invalid because it violates the law of conservation of matter.
Write the formula for the product of the reaction between beryllium and oxygen.
BeO
How can you tell that MTBE (C5H12O) is a covalent compound?
Because it is made of nonmetal elements.
Balance the equation: CH4 → C + H2
CH4 → C + 2H2
Write the formula for calcium hydroxide.
Ca(OH)2
Write the unbalanced equation from the following word equation: Calcium carbonate breaks down into calcium oxide and carbon dioxide.
CaCO3 = Ca(2+) + O(2-) + C(4+) + O2(2-)
What is the correct formula for calcium chloride?
CaCl2
How do we call the solid product that settles out of a solution following a reaction?
Called a precipitate.
What is the oxidation number of the carbon family?
+/-4
What is the charge on a Group 1A element when it loses an electron?
+1
What is the oxidation number of lithium?
+1
What is the oxidation number of the alkali metals?
+1
What is the oxidation number of Fe in FeCl2?
+2
What is the oxidation number of beryllium?
+2
What is the oxidation number of oxygen in OF2?
+2
What is the oxidation number of the alkaline-earth?
+2
What is the oxidation number of Group 3A?
+3
What is the oxidation number of F in AlF3?
-1
What is the oxidation number of the halogens?
-1
What is the oxidation number of the oxygen family?
-2
What is the oxidation number of pure elements?
0
What is the oxidation number of the noble gases?
0
What is the sum of the oxidation numbers of all the elements in a compound?
0
Name four signs that a chemical change may have taken place.
1. Solid separates 2. Gas is produced 3. Color change 4. Temperature change
Balance the chemical equation: FeBr3 + Cl2 → FeCl3 + Br2
2FeBr3 + 3Cl2 → 2FeCl3 + 3Br2
What is the only guarantee that a chemical reaction has occurred?
A new substance is formed.
What area of chemistry involves the study of the energy changes in a chemical reaction?
Chemical thermodynamics
How would you write the element chlorine in a chemical equation? Why?
Cl2(g) because it is a gas and it is diatomic.
Classify the following chemical reaction: 2Hg + O2 → 2HgO
Composition reaction
Is MTBE (C5H12O) a covalent or ionic compound?
Covalent
Classify the following chemical reaction: 2KClO3 →∆ 2KCl + 3O2↑
Decomposition
Classify the following chemical reaction: AgNO3 + NaCl → AgCl↓ + NaNO3
Double-replacement reaction
A plant absorbs sunlight to combine carbon dioxide and water to produce sugars. What two reactions can this chemical change be classified as?
Endothermic and composition
A plant absorbs sunlight to combine carbon dioxide and water to produce sugars. What two kinds of reactions can occur when you digest food from plants to produce carbon dioxide, water, and heat that warms your body?
Exothermic and decomposition
Elements can have only one characteristic oxidation number. (True/False)
False
In a chemical reaction, both the kinds of atoms and their arrangements change. (True/False)
False
Since compounds have no electrical charge, oxidation numbers do not really apply to the compound formula as a whole. (True/False)
False
The charge of an ion and its oxidation number are the same thing. (True/False)
False
Write the unbalanced equation from the following word equation: Iron combines with sulfur to produce iron (I) sulfide.
Fe(2+) + S(2-) = FeS
What is the most helpful for determining the oxidation number of an atom?
Group
What is the name of OH-?
Hydroxide ion
What is the distinguishing feature of a decomposition reaction
Is a single reactant
What is the distinguishing feature of a composition reaction
Is the formation of a single product
What is the distinguishing feature of a single-replacement reaction
Is the presence of both an element and a compound before and after the reaction
What is the distinguishing feature of a double-replacement reaction
Is the presence of two reactants and two products whose ions exchange places. A precipitate often forms.
What is the balanced chemical equation?
It is balanced when the number of atoms of each element is the same on both sides of the equation.
Name PbCl2.
Lead (II) chloride
What is the correct formula for the compound of magnesium and the nitrate ion?
Mg(NO3)2
To write a chemical formula, we must know the _________________.
Oxidation numbers
What are the products and reactants of a chemical change?
Reactants are the substances changing and the products are the substances produced by the change.
What is the name of Ag2O?
Silver oxide
Classify the following chemical reaction: 2Na + 2HOH* → 2NaOH + H2↑
Single-replacement reaction
Classify the following chemical reaction: Fe2O3 + 2Al → 2Fe + Al2O3
Single-replacement reaction
Classify the following chemical reaction: Mg + 2Hcl → MgCl2 + H2↑
Single-replacement reaction
What part of a chemical formula tells the number of atoms of each element?
Subscript
If an element symbol in a chemical formula has no subscript, what is assumed?
That there is only one element.
What is the empirical formula?
The simplest whole number ratio of atoms of each element in a compound
What information does a chemical equation provide?
They tells use what chemicals are present at the beginning of a chemical change and what are present afterwards. They also allows us to account for the number of atoms throughout the reaction.
Why do chemists sometimes include special symbols in chemical equations?
To show the physical state of reactants or products and shows the condition of how the reaction occurs
A binary compound can have more than two atoms in its formula. (True/False)
True
Covalent and ionic compounds are named differently. (True/False)
True
If an element symbol appears in a chemical formula, at least one atom of that element is in the molecule. (True/False)
True
In a binary compound the less electronegative element is also the one with the positive oxidation number. (True/False)
True
The empirical formula for a covalent compound is the smallest ratio of element atoms in the molecular formula. (True/False)
True
Thermal decomposition of a compound always produces two or more products. (True/False)
True
What must usually be added to make a compound decompose?
Usually electrical or thermal energy is necessary.
How can you indicate that the solid product settled out of a solution following a reaction?
With a down arrow (↓)
Is this a composition reaction: N2 + 3H2 → 2NH3
Yes
Is this a decomposition reaction: 2BaO → 2Ba + O2
Yes
Is this a double-replacement reaction: Mg(OH)2 + 2HCl → MgCl2 + 2H2O
Yes
Is this a single-replacement reaction: SiCl4 + 2H2 → Si + 4HCl
Yes
