Quiz-Counting Atoms (IGCSE CHEMISTRY)

Quiz-Counting Atoms (IGCSE CHEMISTRY)

quiz   19:40

QUIZ – COUNTING ATOM

NAME/#        : __________________________

DAY, DATE        : __________________________        

1. Calculate the volume of the 3.2 g of sulphur trioxide gas at r.t.p condition and at s.t.p condition

Ans:

2.  A sample of carbon monoxide gas, CO, has volume of 6 dm3 at r.t.p.

1. How many moles of the gas are there in the sample?

Ans:

2. How many particles are there

Ans:

3. What is the mass of the sample?

Ans:

3. An unknown compound is analyzed and found to consist of 24.3 % carbon, 4.1 % hydrogen, and 71.6 % chlorine.  If the molecular mass of the compound is 98.8, what is the molecular formula of the compound?

Ans:

4. The element boron forms several compounds that contain only boron and hydrogen. A sample of one of these compounds weighing 56 g was found to contain 44 g of boron.

1. Find the ratio of the number of hydrogen atoms to the number of boron atoms in the compound.

Ans:

2. The rtelative molecular mass of the compound is 28. Write the chemical formula for this compound of boron and hydrogen.

Ans:

5. Hydrated sodium carbonate has the formula Na2CO3.nH2O. on strong heating, Hydrated sodium carbonate decomposes completely into water and anhydrous sodium carbonate, CuSO4. The formula of Hydrated sodium carbonate was found by the following procedure.

                

        A mass of Hydrated sodium carbonate was heated strongly in a crucible until decomposition was complete.

                        

the following result was obtained.

Mass of empty crucible = 11.50 g

Mass of crucible +         hydrated copper(II) sulphate = 17.22 g

Mass of crucible + anhydrous copper(II) sulphate =  13.62 g

1. Suggest how you could find out when the decomposition of Hydrated sodium carbonate is complete                                                                                

Ans:

2. Calculate the mass of water evaporated  in the decomposition, and the number of moles of the water.        

Ans:                                                                                 

3. Calculate the mass of anhydrous sodium carbonate produced in the decomposition, and the number of moles of Na2CO3                                                                     

Ans:

4. Find the value of n in the formula                                                            

Ans:

HOME QUIZ CP1 - ACID_BASE

HOME QUIZ CP1 - ACID_BASE

Acids and Bases   05:15

Dear CP1, here is your last Home Quiz. You can use this quiz to practice. I hope it can help your preparation for the upcoming Final Test. GBU


This is a Acids-Bases Quiz (Multiple Choice Question), for Checkpoint 1 (grade 7)

Klik here to attempt the quiz 

Key Answer

Klik here to download the key answer

Review: Acids and Bases for Checkpoint

Review: Acids and Bases for Checkpoint

Neutralisation   19:36

Acids

¢  An acid is a compound/substance that produces hydrogen ions (H⁺) when dissolved in water

¢  Acids taste sour.

¢  Acids turn indicators red

¢  An acid has pH lower than 7

Bases

¢  Bases are ionic compounds that produce hydroxide ions (OH^-) when dissolved in water .

¢  Bases taste bitter and feel slippery

¢  Bases turn indicators blue

¢  Bases release hydroxide ions in water solutions (the more released, the stronger the base)

¢  Has pH more than 7; pH range  7-14

Indicators

¢  Indicators are weak organic acids or bases which have the property of changing color in solution when the hydrogen ion concentration reaches a definite value.

¢  The most used indicator is litmus (extracted from lichens)

¢  Blue paper litmus changes color to red in acid solution

¢  Red paper litmus turns blue in alkali solution

Acids Affect Indicators, by changing their color

Blue litmus paper turns  red  in contact with an acid  (and red paper stays red).

Bases Affect Indicators

Red litmus paper turns  blue  in contact with a base (and blue paper stays blue).

Phenolphthalein turns purple in a base.

The pH scale

¢  The pH scale is a measure of the hydrogen ion concentration, the scale runs from 0 to 14

¢  Acids have pH less than 7, more strength acid, the lower the pH

¢  Neutral substances have a pH of 7

¢  Bases have pH 7 to 14, more alkaline in solution, the higher the pH

¢  The pH of a solution can be measured by universal indicator paper and pH meter

More on pH

¢  If you add an acid to water, the concentration of hydrogen ions increases and the concentration of hydroxide decreases. 

¢  The lower the pH value, the greater the hydrogen ion concentration.

¢  If you add base to water the concentration of hydroxide increases and the hydrogen ion concentration decreases.

¢  The higher the pH value, the lower the hydrogen ion concentration.

Common Acids and Bases

Acids

¢  Hydrochloric acid   HCl

¢  Nitric acid                            HNO₃

¢  Sulphuric acid                    H₂SO₄

_Bases

¢  Sodium hydroxide   NaOH

¢  Calcium hydroxide Ca(OH)₂

¢  Magnesium hydroxide   Mg(OH)₂

¢  Ammonium hydroxide  NH₄OH

WORKSHEET

1.       Name 2 acids and their uses.

 2.       Name 2 bases and their uses.

 3.       Describe one way you can safely determine whether an unknown solution is an acid or base?

4.     How can an acid be neutralized?

Acid Base Worksheet

Acid Base Worksheet

Chemistry   10:40

Here are the pointer to review for upcoming midterm test:

1. Kinetic theory of matter:

    -  The properties of solid, liquid and gas based on the kinetic theory of matter;

    -  gas pressure;

    -  dissolving process;

    -  diffusion;

2. Acids and Bases

    -  Acids and Bases properties;

    -  Indicators;

    -  pH;

    -  Examples of acids/bases

Workout these following question in your "EXERCISE BOOK" only. Submit it after Chemistry Test (Monday, March 10) on Mr. Markus desk.

1. State the characteristics/properties of acids and bases (4 characteristic)                                 [8]

ACIDS PROPERTIES	BASES PROPERTIES

    2. Fill in the blank in the table below, if P = alkali, Q = acid. The litmus paper turns in color.

Solution	P	Q
red litmus paper
blue litmus paper

                                                                                                                                                   [4]

       What are the other acid base indicators instead the litmus paper? [2]

3.  Sweat from the skin is slightly acidic and reacts with jewellery containing nickel.

(i)                  Suggest how you could find out the pH of the sweat on the surface of your skin. [2]

  

(ii)               Which one of the values represents a pH which is slightly acidic.

Put a ring around the correct answer. [1]

  

pH 2                               pH 6                       pH 7                      pH 8                      pH 13

4. A solution of perfume has a strong smell.

A beaker of perfume solution is put in the corner of a room which is free of draughts. At first, the girl by the closed window cannot smell the perfume. After 30 seconds she smells the perfume.

Use the kinetic particle theory to explain these facts. [2]

Acids Bases Worksheet - Lower Secondary Checkpoint

Acids Bases Worksheet - Lower Secondary Checkpoint

Chemistry   08:43

ACIDS and BASES WORKSHEET-1

Most people think of acids as corrosive liquids which fizz when they come into contact with solid and burn when they touch the skin. The word acid comes from the latin word acidus meaning sour. As bases neutralise acids they are sometimes described as having properties which are opposite to acids. (Cambridge Checkpoint, Peter D Riley)

Answer the following questions.

1. Why does wine go sour faster if the cork is removed from the bottle?
2. How do you think the term of organic acid? Give example.
3. How is a dilute solution different from a concentrated one?
4. Which of the following substances are bases – copper chloride, sodium hydroxide, calcium carbonate, magnesium sulphate, copper oxide, lead nitrate, sodium hydrogen carbonate?
5. Why are bases sometimes described as opposite of acids?
6. How are acids and bases similar?
7. Write word equations for the reactions between:

a.      Sulphuric acid and zinc oxide

b.      Hydrochloric acid and calcium hydroxide

c.       Nitric acid and calcium carbonate

d.      Hydrochloric acid and zinc carbonate
8.    How is the neutralisation of a carbonate different from the neutralisation of an oxide or a hydroxide?

Acid-Base Worksheet

Acid-Base Worksheet

Chemistry   12:20

To download PDF form clik the link below:

click to download