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Bell Work. Convert the following to a chemical equation. Iron (III) chloride reacts with magnesium phosphate to form magnesium chloride and iron (III) phosphate. Physical Science – Lecture 46. Intro to Balancing Chemical Equations. Chemical Equations.
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Bell Work • Convert the following to a chemical equation. • Iron (III) chloride reacts with magnesium phosphate to form magnesium chloride and iron (III) phosphate.
Physical Science – Lecture 46 Intro to Balancing Chemical Equations
Chemical Equations • In a chemical equation, there are certain numbers of elements on the reactant side and on the product side.
Law of Conservation of Mass • Law of Conservation of Mass says that in a chemical reaction, the mass of the products equals the mass of the reactants. • This is true because mass cannot be created or destroyed.
What does this mean for Chemical Equations? • The number of each element (not compound) on each side must be equal since mass cannot be created or destroyed.
How do we count elements in equations? • Multiply the coefficient times the subscript for each element in a chemical formula. • If the chemical formula has parenthesis, the subscript outside the parenthesis is also multiplied by all elements inside the parenthesis.
Example • CO2
Example • Mg3(PO4)2
Practice • CH3COOH
Practice • (NH4)2CO3
Example with Coefficients • 2 NaCl
Example with Coefficients • 6 Mn2O3
Example with Coefficients • 4 Be3(PO4)2
Practice • 3 BeF2
Practice • 3 LiNO3
Practice • 2 Ca3(PO4)2
Balancing an Equation Rules • Apply the Law of Conservation of Mass to get the same number of atoms of every element on each side of the equation.
How to Balance an Equation • Draw a chart with elements from the reactant side on the left and elements from the product side on the right.
How to Balance an Equation • Multiply each element by any number that will make the two sides (reactant and product) equal.
How to Balance an Equation • When multiplying, if an elements is in the same chemical formula as another, you must also multiply that element by the same number.
How to Balance an Equation • If one element appears in more than one formula, place the element in two separate blocks and add the total number of them together.
How to Balance an Equation • Balance chemical formulas by placing coefficients in front of them. Do not add subscripts, because this will change the formulas.
Tip • Start by balancing an element that appears in only one reactant and product.
Bell Work Example – Is it Balanced? • 2 FeCl3+ Mg3(PO4)2--> 3 MgCl2+ 2 FePO4
Example – Is it Balanced? • 1 AgNO3 + 1 LiOH --> 1 AgOH + 1 LiNO3
Example – Balancing an Equation • Find the missing number to balance the equation: • 2 FeCl3 + 1 Be3(PO4)2 --> ___ BeCl2 + 2 FePO4
Practice – Balancing an Equation • Find the missing number to balance the equation: • ___ CH4+ 2 O2 --> 1 CO2 + 2 H2O
Practice – Balance the Equation • Find the missing number to balance the equation: • 3 Mg + 1 Mn2O3 --> ___ MgO + 2 Mn
Practice – Balance the Equation • Find the missing number to balance the equation: • 2 AlBr3 + 3 Ca(NO3)2 --> 3 CaBr2 + ___ Al(NO3)3