Chemical Equations Define a chemical reaction Describe and

Chemical Equations Define a chemical reaction Describe and explain why mass is conserved TBAT balance symbol equations KEYWORD: conservation of mass STARTER: Sodium + Chlorine Sodium Chloride What are the ‘reactants’ and ‘products’? EXT: Write a word equation from this statement “Hydrogen gas and oxygen gas react to form liquid water. ” 0

What is a chemical reaction? From your discussion, write a definition in your own words. So, what do we mean by: “Conservation of Mass”

Let’s look at a chemical reaction: Hydrogen + Oxygen Water + Does this show us that mass is conserved? Do we have the same number of particles on each side? 10/3/2020

Let’s add another molecule of Water Hydrogen We + Oxygen Water + now have the same number of Oxygen particles on either side, but what about Hydrogen?

How about now? Hydrogen + Oxygen Water +

Chemical Reactions In a chemical reaction… Bonds break New bonds form New substances are made NB: We never change the mass though. Think of baking a cake…. . 10/3/2020

10/3/2020

REVIEW In your own words, try to describe and explain in detail why mass is conserved. You can use diagrams to support your answer, but try and use the keywords below: Conservation of mass Define a chemical reaction Reactant Describe and explain why mass is conserved Product Bonds TBAT balance symbol equations 10/3/2020

Testing for Carbon Dioxide Limewater is calcium hydroxide solution, Ca(OH)2. It forms calcium carbonate, Ca. CO 3, and water when it reacts with carbon dioxide. a Write a word equation for this b Write a balanced symbol equation for this

Calcium + carbon dioxide calcium + water hydroxide carbonate Ca(OH)2(aq) + CO 2(g) Ca. CO 3(s) + H 2 O(l) a Write a word equation for this B Write a balanced symbol equation for this and State symbols – what are these?

It’s all a balancing act! + Write out the chemical formula for each substance first 2 H 2 + O 2 2 H 2 O Now add BIG NUMBERS at the front of the substances to balance out the equations

H 2 + Br 2 → HBr H 2 O 2 → H 2 O + O 2 Li + H 2 O → Li. OH + H 2 Na. NO 3 → Na. NO 2 + O 2 Fe + O 2 → Fe 2 O 3 10/3/2020

H 2 + Br 2 → 2 HBr 2 H 2 O 2 → 2 H 2 O + O 2 2 Li + 2 H 2 O → 2 Li. OH +H 2 2 Na. NO 3 → 2 Na. NO 2 + O 2 4 Fe + 3 O 2 → 2 Fe 2 O 3 10/3/2020

REVIEW (b) Write a balanced symbol equation for the reaction between magnezium (Mg) and oxygen (O 2) to form magnesium oxide (Mg. O). 2 Mg + O 2 Mg. O . . . . . . . . 2 (1 mark) Define a chemical reaction Describe and explain why mass is conserved TBAT balance symbol equations 10/3/2020

1) Ca. F 2 + Li 2 SO 4 Ca. SO 4 + Li. F 2) Al. Br 3 + K KBr + Al 3) Si(OH)4 + Na. Br Si. Br 4 + Na. OH 4) Li 3 PO 4 + Na. Br Na 3 PO 4 + Li. Br 5) Co. Br 3 + Ca. SO 4 Ca. Br 2 + Co 2(SO 4)3 10/3/2020

1) Ca. F 2 + Li 2 SO 4 Ca. SO 4 + 2 Li. F 2) Al. Br 3 + 3 KBr + Al 3) Li 3 PO 4 + 3 Na. Br Na 3 PO 4 + 3 Li. Br 4) Si(OH)4 + 4 Na. Br Si. Br 4 + 4 Na. OH 5) 2 Co. Br 3 + 3 Ca. SO 4 3 Ca. Br 2 + Co 2(SO 4)3 10/3/2020