5.1 NOTES: Acids and Bases - BC Learning...

BCLN SCIENCE 10 - Rev. August/2014

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Unit 5 ~ Learning Guide Name: _____

INSTRUCTIONS Complete the following practice questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test.

Please print out the Formula Sheet found at the start of the course. You will need this to do assignments and tests!

5.1 NOTES: Acids and Bases

General Information

Acids and bases are .

Many familiar compounds are acids or bases. Classification as acids or bases is based on .

Acids and bases can be very !

Both can be very corrosive. o try to identify an acid or base by !

The strength of acids and bases in measured on the pH scale

pH below 7 = acidic, pH above 7 = basic, pH 7 = neutral 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

________ __ ___ ________ _____ _______

Each on the pH scale indicates more acidic o For example, pH 4 is ten times more acidic than pH 5 o


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pH Indicators

The pH of acids and bases cannot be determined by sight.

Instead, pH is other chemicals called , or by a pH meter that measures the electrical conductivity of the solution.

pH indicators based on the solution they are placed in.

is the most common indicator, used on litmus paper. Two colours of litmus paper: Blue = basic and Red = acidic. Blue = pH above 7, Red = pH below 7 contains many indicators that turn different

colours at different pH values (can be in liquid form, or on paper strips like litmus) A uses to

measure how solutions conduct electricity Indicators change colour at different pH values, so

indicators are used to identify values Bromothymol blue for pH 6 - 7.6, phenolphthalein for pH 8.2 - 10 Many natural sources, such as beets and cabbage, are also indicators

Acids

If you know a , you may be able to identify it as an acid.

Acids often behave like acids only when dissolved in water Therefore, acids are often written with subscript (aq) = aquatic = water

The chemical formula of an acid usually starts with

Acids with a carbon usually have the C written first. o = hydrochloric acid, = nitric acid,

= acetic acid

Naming acids

For Acids formed from the periodic table:

Hydrogen + …-ide = Hydro…ic acid o HF(aq) = hydrogen fluoride =

For Acids formed from .


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Hydrogen + …-ate = …ic acid o H2CO3(aq) = hydrogen carbonate =

For Acids formed from .

Hydrogen + …-ite = …ous acid

o H2SO3(aq) = hydrogen sulphite =

Bases

If you know a compound’s chemical formula, you may be able to identify it as a base.

Bases, like acids, often behave like bases only when dissolved in water Therefore, bases are often written with subscript (aq) = aquatic = water

The chemical formula of a base usually ends with

•Examples of common bases

NaOH(aq) Mg(OH)2(aq) Ca(OH)2(aq) NH4OH(aq)

Naming Bases

To name a base you simply name o NaOH (aq) - Sodium hydroxide o Mg(OH)2 (aq) - Magnesium hydroxide

Production of Ions

Acids and bases because they release ions in solution.

Acids release Bases release

The pH of a solution refers to the concentration of (H+/OH-) ions it has.

Square brackets are used to signify concentration, [H+(aq)], [OH–(aq)] o High [H+(aq)] = , very acidic o High [OH–(aq)] = , very basic


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A solution cannot have BOTH high [H+(aq)] and [OH–(aq)]; they cancel each other out and . This process is called .

H+(aq) + OH–(aq) H2O(l )

Properties of Acids & Bases


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5.1 PRACTICE: Acids and Bases

1. Complete the Acid Formulas practice, 5.1 crossword, 5.1 quiz, the Acids Worksheet, and 5.1 Check Your Understanding.

2. Water is a neutral compound. What is the pH of water?

3. How many times more acidic is pH 2 than pH 4?

4. Name two methods used to measure pH.

5. What is the most common indicator? Describe it's color in acid and base.

6. What does it mean when you see (aq)?

7. What letter do most acids start with?

8. What is different about the position of that letter if an acid starts with a C?


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9. Name the following acids:

Formula Name

HBr

H2S

HNO2

HNO3

HClO4

H2CO3

CH3COOH

10. How can you recognize that a given formula is a base?

11. Name the following bases:

Formula Name

KOH

Al(OH)3

NH4OH


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12. Why do acids and bases make good electrical conductors when dissolved in water?

13. What ion does an acid release? What ion does a base release?

14. Why is it not possible to have a solution that is both highly acidic AND highly basic? What is the process called that prevents this from happening?

15. Fill in the table below with the most important information. Do not simply copy everything from the website.

Property Acid Base

Taste

Touch

Color in Litmus

Reaction with metal

pH


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5.2 NOTES: Salts

General Information

Salts are formed when .

Salts are also produced when oxides or carbonates react with acids, or when metals react with acids.

Table salt, , is found in seawater, salt lakes or rock deposits.

Salt was once very valuable as a commodity. Iodine is now added to salt to minimize goiter (a disease of the thyroid)

NaCl is only one kind of salt

A salt is made up of a from a base and Salts are found in many things

o o o

Neutralization & Oxides

Neutralization reactions occur when an react to produce a .

HCl(aq) + NaOH(aq) NaCl(s) + H2O(aq)

Metal oxides react with water to form bases.

Na2O(s) + H2O( l)

Non-metal oxides react with water to form acids

SO2(g) + H2O( l) Non-metal oxides are formed from the burning of fossil fuels

o Add water in the atmosphere =


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Acids with Metals & Carbonates

Acids and Metals

The most reactive metals , react vigorously with water and acids.

All other metals are than those in groups 1 and 2. When metals do react with acids is usually released 2HCl(aq) + Mg(s) MgCl2(s) +

Acids and Carbonates

(-CO3) , protecting locations with natural carbonate supplies from acid precipitation.

H2SO4(aq) + CaCO3(s) CaCO4(s) + H2O(aq) + CO2(g) sulphuric acid + calcium carbonate --> calcium carbonite + water + carbon dioxide

5.2 PRACTICE: Salts

1. Complete quiz 5.2, and 5.2 Check Your Understanding.

2. What type of compounds are salts?

3. What are the three types of reactions that produce salts?

4. What is the formula of table salt?


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5. Name 5 things that may contain a salt?

6. Predict the products of each of the following reactions using the examples in the notes as a guide:

Reactant

s Product

s

H2S(aq) + Ca(OH)2(aq) (Acid) (base)

CaO(s) + H2O( l) (metal oxide) (water)

NO2(g) + H2O( l) (non-metal oxide) (water)

7. What non-metal oxide is the main cause of acid rain?


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5.3 NOTES: Organic Compounds General Information

Organic compounds contain , and usually .

“Organic” sounds like the compounds come from living things, but some do, and some don’t.

are compounds that .

Carbon has electrons in its valence shell, which allows for chemical bonding than any other element.

Long chains of carbons form petroleum and plastics

Organic molecules always have in their formulas

This differentiates organic compounds from acids, which almost always start with H


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Hydrocarbons & Alcohols

A is an organic compound that contains only

.

Hydrocarbons are based on a carbon “backbone”, or chain, with hydrogen atoms added on the sides.

The simplest hydrocarbon is methane ( ), followed by ethane ( ), propane ( ), butane( ), and pentane( )

All hydrocarbons , and most are liquids are room temperature (ie gas)

You will need to know the basic Hydrocarbons below.

Alcohols are organic compounds with

The simplest alcohols are methanol (CH4O), ethanol (C2H6O) and isopropyl alcohol (C3H8O).

Alcohols are very (they dissolve other substances) Alcohols are generally very


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You also need to know the following alcohols.

5.3 PRACTICE: Organic Compounds

1. Complete 5.3 Crossword, 5.3 quiz, and 5.3 Check Your Understanding.

2. Do all organic compounds come from living things?

3. What element MUST be present in organic compounds?

4. What element is almost always present in organic compounds? Hint: CCl4 is an example of an organic compound that does not contain this element.

5. What ion contains carbon but is inorganic? Give the name and the formula


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6. Determine if each of the following is organic or inorganic.

Formula Name

CaCO3

CO2

C2H6O

C4H10

NaHCO3

CuOH

CHF3


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7. Fill in the table below.

Name Formula Common Use

Methane

Ethane

Propane

Butane

Pentane

Methanol

Ethanol

Isopropyl Alcohol


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Unit 5 Le arning Guide Ans we rs

Please note that most answers are directly from the online notes. Answers are given when needed.

Acids and Bases

1-7) Answers directly from the online notes, 8) Hydrobromic acid, Hydrosulfuric acid, Nitrous acid, Nitric acid, Perchloric acid, Carbonic acid, Acetic acid, 9) Answers directly from online notes, 10) Potassium hydroxide, Aluminum hydroxide, Ammonium hydroxide. 11-12) Answers directly from online notes, 12) Answer directly from online notes, 13) acids and bases when added together neurtralize each other, 14) see table from online notes.

Salts: 1-4) Answers directly from online notes, 5) CaS + H2O, Ca(OH)2, HNO2 + HNO3, 6) Sulfur oxides or Nitrogen oxides

Organic Compounds

1)Answer directly from online notes, 2) Carbon, 3) Hydrogen, 4) CO3-2, 5) I, I, O, O, I, I,

O, 6) Methane - CH4 Natural Gas, Ethane - C2H6 Making plastic, Propane - C3H8

Barbeque fuel, Butane - C4H10 Lighters, Pentane - C5H12 Gasoline, Methanol - CH4O solvent, Ethanol - C2H6O Fuel, Isopropyl Alcohol - C3H8O, Cleaner

5.1 NOTES: Acids and Bases - BC Learning...

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