Pre-Lecture Chapter 7 General Chemistry 1

What is the overall balanced equation for the precipitation reaction occurring between silver nitrate and calcium bromide?

2AgNO3(aq)+CaBr2(aq)→2AgBr(s)+Ca(NO3)2(aq)

What is a chemical equation?

A chemical equation is a way of representing what happens to atoms and molecules during a chemical reaction.

Which of the following compounds will NOT help relieve heartburn? CaCO3 Mg(OH)2 HCl Al(OH)3

HCl

Consider the following ionic compounds: CdCO3, Na2S, PbSO4, (NH4)3PO4, and Hg2Cl2. Which compounds will be soluble when added to water? a. Na2S and (NH4)3PO4 b. CdCO3, PbSO4, and Hg2Cl2 c. Hg2Cl2, Na2S, and (NH4)3PO4 d. Hg2Cl2

Na2S and (NH4)3PO4

In a redox reaction...

electrons are exchanged between the reactants.

Reactions that immobilize ions in hard water are called _____________.

precipitation reactions

What does it mean if a compound is referred to as soluble? Insoluble?

1. An insoluble compound will hardly dissolve in solution at all. 2. A soluble compound will dissolve in solution in appreciable quantities.

Making sure the default volume of water is 1.00×10−16 L when using the Slightly Soluble Salts tab, add each of the possible salts to the water. Observe how much salt dissolves before the solution becomes saturated. Arrange the following salts according to their solubility in water. Rank the salts from most soluble to least soluble.

1. silver arsenate 2. copper(I) iodide 3. silver bromide 4. thallium(I) sulfide

Identify the reactants and products. 2HCl + Ba(OH)2 = BaCl2 + 2H2O

2HCl + Ba(OH)2 = reactants BaCl2 + 2H2O = products

Provide the example(s).

> 2H2(g)+O2(g)→2H2O(l) > HBr(aq)+NaOH(aq)→NaBr(aq)+H2O(l) > 2HCl(aq)+Ba(OH)2(aq)→BaCl2(aq)+2H2O(l)

Which of the following general reactions appropriately models a combination reaction? a. C → A + B b. A + B → C + D c. A + B → A + B d. A + B → C

A + B → C

What is a precipitation reaction?

A precipitation reaction occurs when two aqueous mixtures containing only soluble compounds are mixed together and the formation of insoluble solid compound takes place.

Identify the precipitate of Ba(NO3)2+Na2SO4→BaSO4+2NaNO3 . Express your answer as a chemical equation. Identify all of the phases in your answer.

Ba(NO3)2(aq)+Na2SO4(aq)→BaSO4(s)+2NaNO3(aq)

Choose an example of precipitation reaction.

Ba(NO3)2+Na2SO4→BaSO4+2NaNO3

In an acid-base reaction...

H+ ions reacts with OH− ions.

Which of the following compounds decompose to form water and a gas?

H2CO3

Go to the Slightly Soluble Salts tab. Choose a salt from the dropdown menu to the right. Mouse over the salt shaker and move your mouse up and down while clicking the left mouse button to add the salt to the container of water. You can also add and remove water from the container by moving the sliders on the faucets to the left of the container back and forth. Notice that there is a table indicating the number of dissolved and bound (solid) ions to the right under the dropdown menu. Using the data in this table, enter the chemical formula of mercury(II) bromide.

HgBr2

Which reaction is a decomposition reaction? a. C2H4(g) + O2(g) → CO2(g) + H2O(g) b. Li(s) + N2(g) → Li3N(s) c. NH4NO3(s) → N2O(g) + H2O(g) d. CO(g) + 12O2(g) → CO2(g)

NH4NO3(s) → N2O(g) + H2O(g)

Balancing chemical reactions is consistent with which scientific law?

law of conservation of mass

In a combustion reaction...

substance reacts with oxygen to form oxygen-containing compounds.

What precipitate will form when aqueous solutions of sodium carbonate (Na2CO3) and calcium chloride (CaCl2) are mixed?

CaCO3(s)

What are the products of the precipitation reaction between aqueous potassium iodide, KI, and aqueous lead(II) nitrate, Pb(NO3)2?

PbI2 and KNO3

Which of the following symbols represents a solution in a chemical reaction? a. (aq) b. (l) c. (s) d. (g)

(aq)

What does each abbreviation, often used in chemical equations, represent? (g) (l) (s) (aq)

(g) = gas (l) = liquid (s) = solid (aq) = aqueous

How are they useful?

- These rules are useful because there is no way to predict solubility from looking at the periodic table. - These rules allow us to know what compounds will dissolve in water and which ones will not, which is critical when writing chemical equations.

What are the main indications that a chemical reaction has occurred?

- emission of light - a color change - formation of a gas - formation of a solid - emission of (or absorption of) heat

If you could observe atoms and molecules with the naked eye, what would you look for as conclusive evidence of a chemical reaction?

- original compounds decompose - atoms are exchanging places with atoms in another compound - atoms are combining with other atoms to form a compound - new molecules are formed

Part B: Choose the example(s).

- the neutralization of acid with a base - iron rusting

Write an equation for the precipitation reaction that occurs (if any) when solutions of potassium hydroxide and nickel(II) bromide are mixed.

2KOH(aq)+NiBr2(aq)→Ni(OH)2(s)+2KBr(aq)

Given the rule that all compounds containing Li+, Na+, K+, NH4 +, NO3 −, and C2H3O2 − ions are soluble, which of the following is insoluble?

CaCO3

Part A: What is a chemical reaction?

In a chemical reaction, one or more substances change into different substances.

Which of the following would be written as two separate ions in a complete ionic equation?

KNO3(aq)

Which of the following is a chemical reaction? a. solid ice water changing to liquid water b. liquid water changes to gaseous oxygen and hydrogen molecules. c. liquid molecules changing to gas water molecules d. water molecules mixing with sugar molecules

liquid water changes to gaseous oxygen and hydrogen molecules.

If you carry out the reaction between table salt (NaCl) and ammonium phosphate ((NH4)3PO4) in 100.0 mL of water, the salt ammonium phosphate will behave similarly to the salts given in the tab named Slightly Soluble Salts. Enter the formula for the precipitate, without the phase, that will be formed. If no precipitate is formed, simply type "noreaction" in the answer box.

noreaction

In a gas evolution reaction...

one of the products of a chemical reaction is a gas.

Explain what happens to an ionic substance when it dissolves in water.

Ionic compounds dissolve in water and dissociate into the ionsIonic compounds dissolve in water and dissociate into the ions that make up the compound. For example, NaCl in water will form N a + ( a q ) (element of the I group) and C l − ( a q ) (element of the VII group).

Which of the following are spectator ions in the reaction: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

Na+ and NO3 −

Predict the products for the following precipitation reaction: NiCl2(aq)+(NH4)2S(aq)→

NiS(s)+2NH4Cl(aq)

Is the chemical equation balanced? C3H8(g)+O2(g)→3CO2(g)+4H2O(g)

No, the equation is not balanced.

What are the solubility rules?

Soluble compounds: - Any compound containing Li+, Na+, K+, or NH+4. - Any compound containing NO−3 or C2H3O−2. - Most compounds containing Cl−, Br−, or I− (except with Ag+, Hg2+2, or Pb2+). - Most compounds with SO2−4(except with Sr2+, Ba2+, Pb2+, or Ca2+). Insoluble compounds: - Most compounds containing OH− or S2− (except with Li+, Na+, K+, or NH+4; except when S2− is with Sr2+, Ba2+, or Ca2+; except when OH− is with Sr2+, Ba2+, or Ca2+). - Most compounds containing CO2−3 or PO3−4 (except with Li+, Na+, K+, or NH+4).