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Grade 12 Challenge: Chemistry in the Real World Worksheet with Answers

Grade 12 (US) · Year 13 (UK) · Class 12 (India) · Science

Unit 5: Going FurtherReal-World ChallengesChallenge

Stoichiometry that matters: airbags, a tank of petrol's CO₂, tyre pressure in winter, medicine half-lives and dilutions. This free high school worksheet has 12 questions and a full answer key. Print it or save it as a PDF — every answer is checked by code, not guessed.

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Challenge: Chemistry in the Real World

Grade 12 · Science

Score___ / 12

Name

Class

Date

Learning goal: Real-World Challenges

Directions: Read each question carefully and write your answer on the line.

Example

A patient takes 400 mg of a drug with a half-life of 4 hours. How many mg remain after 30 hours, to 1 decimal place?

Answer: 2.2

  1. 1

    Heating 10 g of limestone, CaCO₃ (100.09 g/mol), gives quicklime, CaO (56.08 g/mol), and CO₂. A student collects 4.9 g of CaO. What is the percent yield, to 1 decimal place?

  2. 2

    Car airbags inflate when sodium azide decomposes: 2 NaN3 → 2 Na + 3 N2. How many grams of sodium azide (65.01 g/mol) are needed to make 60 L of nitrogen at STP (22.4 L/mol)? Give 1 decimal place.

  3. 3

    A strong acid has pH 2. To make its pH 4, how many mL of water must you add to 10 mL of it?

  4. 4

    A patient takes 500 mg of a drug with a half-life of 4 hours. How many mg remain after 24 hours, to 1 decimal place?

  5. 5

    A patient takes 800 mg of a drug with a half-life of 6 hours. How many mg remain after 30 hours, to 1 decimal place?

  6. 6

    6 g of hydrogen (2.016 g/mol) reacts with 80 g of oxygen (32.00 g/mol): 2 H₂ + O₂ → 2 H₂O. What is the greatest mass of water (18.02 g/mol) that can form, in grams to 1 decimal place?

  7. 7

    Petrol is mostly octane, C₈H₁₈ (114.23 g/mol), with density 0.70 kg/L. It burns as 2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O. How many kg of CO₂ (44.01 g/mol) does a 40 L tank produce? Give 1 decimal place.

  8. 8

    A strong acid has pH 2. To make its pH 4, how many mL of water must you add to 50 mL of it?

  9. 9

    Car airbags inflate when sodium azide decomposes: 2 NaN3 → 2 Na + 3 N2. How many grams of sodium azide (65.01 g/mol) are needed to make 70 L of nitrogen at STP (22.4 L/mol)? Give 1 decimal place.

  10. 10

    Heating 50 g of limestone, CaCO₃ (100.09 g/mol), gives quicklime, CaO (56.08 g/mol), and CO₂. A student collects 20.2 g of CaO. What is the percent yield, to 1 decimal place?

  11. 11

    A strong acid has pH 1. To make its pH 2, how many mL of water must you add to 10 mL of it?

  12. 12

    6 g of hydrogen (2.016 g/mol) reacts with 16 g of oxygen (32.00 g/mol): 2 H₂ + O₂ → 2 H₂O. What is the greatest mass of water (18.02 g/mol) that can form, in grams to 1 decimal place?

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Teacher's comments

Free printable worksheets with answer keys · aethelsystems.com/worksheets/science/12/challenge_chemistry_world

Answer key (click to show)
  1. 1.87.5%
  2. 2.116.1
  3. 3.990
  4. 4.7.8
  5. 5.25.0
  6. 6.53.6
  7. 7.86.3
  8. 8.4950
  9. 9.135.4
  10. 10.72.1%
  11. 11.90
  12. 12.18.0

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