Bell Work What is the chemical formula for Barium Hydroxide? What is the formula for Calcium Nitrate?

Physical Science – Lecture 44 Writing Chemical Equations

Parts of a Chemical Reaction Coefficients – Go in front of the chemical formula. They indicate how many of each chemical is used in the reaction.

Parts of a Chemical Reaction Reactants – The chemicals that are reacting in the chemical reaction. They “react” during the reaction. They are written on the left of the arrow.

Parts of a Chemical Reaction The Arrow – an arrow separates the reactants from the products in a chemical equation.

Parts of a Chemical Reaction Products – The chemicals that are produced by the chemical reaction. They “are formed” from the reaction. They are written on the right of the arrow.

Parts of a Chemical Reaction The plus sign – the plus sign separates a reactant from another reactant or a product from another produce in a chemical reaction.

Parts of a Chemical Equation

Translating Word Equations Word equations must be translated to chemical equations to determine exactly what is happening in a given reaction.

Elements in an Equation All elements when alone are written without charges or subscripts. The only exceptions are the diatomic gases – they all have a small subscript 2 behind them. N 2, O 2, F 2, Cl 2, I 2, Br 2, and H 2

How to Write a Chemical Equation Step 1: Translate each compound name to its chemical formula. (Balance the charges of the cation/anion. OR Add subscripts to replace pre-fixes of mono, di, tri, tetra.) Step 2: Translate words describing the reaction into symbols.

Words Describing the Reaction WordSymbol Reacts with+ And+ To yield or yield→ To form→ Things ReactingGo on the Left of the arrow (→) Things being FormedGo on the Right of the arrow (→)

Example When calcium hydroxide reacts with hydrochloric acid (HCl), calcium chloride and water are formed.

Step 1: Write the unbalanced equation by translating the written names into chemical formulas In this case, the formulas you need to know are those for calcium hydroxide, hydrochloric acid, calcium chloride, and water. What are the formulas for these compounds?

Step 2: Translate the words into symbols When Ca(OH) 2 reacts with HCl, CaCl 2 and H 2 O are formed

When you translate these into their formulas, you should get this equation: Ca(OH) 2 + HCl --> CaCl 2 + H 2 O

Example 2 When Tin (II) Oxide reacts with a stream of Hydrogen gas, Tin Metal and water is formed.

Practice When potassium nitrate reacts with hydrogen carbonate, nitric acid (HNO 3 ) and potassium carbonate are formed.

Practice Methane (CH 4 ) reacts with Oxygen gas to form carbon dioxide and water.

Practice Iron and carbon dioxide are formed from the reaction between Iron (III) Oxide and carbon monoxide.

Carbon dioxide reacts with lithium sulfide to produce carbon disulfide and lithium oxide.

Magnesium fluoride reacts with lithium carbonate to form magnesium carbonate and lithium fluoride.

Sodium fluoride reacts with bromine to form sodium bromide and fluorine.

Aluminum bromide reacts with potassium sulfate to form potassium bromide and aluminum sulfate.

Sodium phosphate reacts with calcium chloride to form sodium chloride and calcium phosphate.