Presentation on theme: "Practice makes perfect. Balancing equations Balancing equations strategy Write the equation unbalanced Look at the most complex substance and balance,"— Presentation transcript:
Balancing equations strategy Write the equation unbalanced Look at the most complex substance and balance, remember to add co efficiency! Go through each element Make sure the coefficiencies are the lowest
For example This is balanced, but the coefficient is not the smallest whole number (divide by two) Most importantly CHECK YOUR ANSWER, by recounting the atoms
Moles & Masses Remember to look at the units (Kg vs. g)
Respiration C 6 H 12 O 6 +O 2 → CO 2 + H 2 0 Alkanes C 7 H 16 +O 2 → CO 2 + H 2 0 Thermite (demonstrate?) Fe 2 O 3 +2Al → Al 2 O 3 + 2Fe Balancing these equations...
Respiration C 6 H 12 O 6 +6O 2 → 6CO 2 + 6H 2 O Alkanes C 7 H 16 +11O 2 → 7CO 2 + 8H 2 O Thermite (demonstrate?) Fe 2 O 3 +2Al → Al 2 O 3 + 2Fe Balanced equations answers
Calculating the amount of atoms Calculate the amount of moles Multiply the number of moles by 6.02 x 10 23
Some examples..... How many atoms in a)78g of H 2 b)64g of methane (CH 4 ) c)41g of calcium nitrate (Ca(NO 3 ) 2 For How many atoms in a)78g of H 2 b)64g of methane (CH 4 ) c)41g of calcium nitrate (Ca(NO 3 ) 2
Working out reacting masses CIp8 Write a balanced equation Write the amount of moles of each substances Write the masses in grams Calculate for 1 gram of product Multiply for the mass given in the question
Exam practice 1.Each pair has one question 2.Answer it individually (5 mins) 3.Discuss your answers with your partner (4 mins) 4.Come up with a final answer Move to the next question on another desk
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