Complete the table. Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Ammonium nitrate 1 Sodium carbonate 2 Na 2 CO 3 Ammonium hydroxide 1 Magnesium carbonate 2 MgCO 3 Iron phosphate Fe + +

Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Ammonium nitrate N H 4 + N O 3 - 1 1 NH 4 NO 3 All compounds are electrically neutral. Hence, ammonium ion has one positive charge and nitrate ion one negative charge. So, both combine to form a neutral compound ammonium nitrate Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Sodium carbonate 2 Na + C O 3 - - 2 2 Na 2 CO 3 Carbonate anion carries two negative charges and sodium cation carries on positive charge. Hence, one carbonate ion combines with two sodium atoms to form electrically neutral sodium carbonate compound. Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Ammonium hydroxide N H 4 + OH - 1 1 NH 4 OH Ammonium carries one positive charge and combines with one hydroxyl ion(one negative charge) to form ammonium hydroxide which is electrically neutral. Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Magnesium carbonate Mg 2 + C O 3 - - 2 2 MgCO 3 Magnesium cation carries two positive charges and carbonate anion carries two negative charges. So, one magnesium ion combines with one carbonate ion to form magnesium carbonate compound. Name of compound Radicals present No. of charges Formula of compound positive negative positive negative Ammonium nitrate N H 4 + N O 3 - 1 1 NH 4 NO 3 Sodium carbonate 2 Na + C O 3 - - 2 2 Na 2 CO 3 Ammonium hydroxide N H 4 + O H - 1 1 NH 4 OH Magnesium carbonate Mg 2 + C O 3 - - 2 2 MgCO 3 Iron phosphate 3 Fe + + 2 P O 4 3 - 6 6 Fe 3 PO 4 2

Express the following reaction using the mole concept. 1 2 Al 2 O 3 + 3 HCl → AlCl 3 + 1 1 2 H 2 O .

1 2 mole of alumina combines with 3 moles of hydrochloric acid to form one mole of aluminium chloride, and 1 1 2 moles of water. For compounds or molecules: Number of moles(n) = Given mass (m) / gram molecular weight (W). A Mole concept gives us the number of particles in a definite amount of any substance.

E M B I B E

Science (Theory & Practical) Class-9>Chapter 9 - Chemical Formula and Mole Concept>Questions>Q 4

MEDIUM

9th Chhattisgarh Board

IMPORTANT

Earn 100

Calculate the formula unit mass of the following compound.

$CaO$

Important Questions on Chemical Formula and Mole Concept

HARD

9th Chhattisgarh Board

IMPORTANT

Science (Theory & Practical) Class-9>Chapter 9 - Chemical Formula and Mole Concept>Questions>Q 1

Complete the table.

Name of compound	Radicals present		No. of charges		Formula of compound
Name of compound	positive	negative	positive	negative	Formula of compound
Ammonium nitrate			1
Sodium carbonate				2	${Na}_{2} {CO}_{3}$
Ammonium hydroxide				1
Magnesium carbonate			2		${MgCO}_{3}$
Iron phosphate	${Fe}^{+ +}$