Lab #1: Popcorn Half-Life

Name:

Introduction: Lab Rubric **Half life (t1/2) is the time it takes for 50% of an unstable "parent" isotope to decompose into a more stable "daughter" isotope**. Each radioactive "parent" isotope has a different half life time. Ex Carbon-14 is 5730 years and Uranium-238 is 4.5 billion years. Check the all boxes that are true.

• After 1 half-life there will be approximately 50% Parent and 50% Daughter.
• After 2 half life there will be approximately 25% Parent and 75% Daughter.
• After 3 half-lives there will be approximately 12.5% Parent and 87.5% Daughter.
• After 2 half-lives there will be approximately 50% Parent and 50% Daughter.
• After 3 half-lives there will be approximately 50% Parent and 50% Daughter.

Raw Data: Lab Rubric : Collect your data from other classmates and add your data to the Spread Sheet. Then add the data to your notebook.

• The raw quantitative (numerical) or qualitative (descriptive) data is organized in neat data tables.
• Quantitative Data is recorded with proper Precision (decimal places).
• Proper units of measurement are indicated on the data table.

Analysis: Lab Rubric Check Boxes as you complete the tasks in your lab notebook. In this lab we used the spread sheet to calculate the **mean and the median** **Means and the medians will be used to determine if there are any outliers. ONLY identied Outliers when you perform 5 or more trials or share data with 5 or more lab groups using the same variables and controls.**

• Raw quantitative data processed Correctly showing, labeling, and explaining ALL calculations with proper 🮖**Sig Figs** and 🮖**Units**. Variations in qualitative data are discussed.
• **Outliers** are identified and excluded if more than one trial, **Percent Errors** and/or **Percent Yields** are labeled and calculated correctly. Extreme variations in qualitative data are discussed.
• Any graphs are constructed using a ruler and axes are labeled. Continuous vs. Discrete are graphed appropriately.
• calculate the **mean and the median** for each level of independent variable which was time (20,30,40 sec).
• Graph your class data in your notebook.

Conclusion: Lab Rubric Check Boxes as you complete the tasks in your lab notebook.

• Accurately and Specifically Explain the validity of each hypothesis compared to the data analysis. Create an alternate hypothesis if your hypothesis was not proved.
• Discuss errors/outliers (large or small) and identify them as **Systematic or Random** *lab conditions can have potential influences*
• Make suggestions to improve the methodology (procedure) to improve **Accuracy and Precision** of data collected. Justify improvements with an explanation.

Watch the video and work the problems out with the instructor and then answer the question below. Half-Life Practice Problems. #1 120g of Radium-223 radioactively decays. How much would remain after 44 days if the Half-Life is 11 Days?

• 7.5g
• 1.7125g
• 3.25g
• 15g
• 30g

Watch the video and work the problems out with the instructor and then answer the question below. Half-Life Practice Problems. #2 Hydrogen-3 has a Half-Life of 12.3 Years. An 80g sample of Hydrogen-3 decays, leaving 2.5g of Hydrogen-3. How long would this take?

• 36.9 years
• 47.2 years
• 61.5 years
• 73.8 years
• 86.1 years

Watch the video and work the problems out with the instructor and then answer the question below. Half-Life Practice Problems. #3 You start with 200g of Thallium-207. After 20 minutes, there is only 12.5 of Thallium-207 left. What is the Half-Life of this decay process?

• 3.33 minutes
• 4 minutes
• 5 mintues
• 6.66 minutes

Half-Life Practice Problems. Uranium – 238 alpha decays with a Half-Life of 4.51 billion years. If a rock sample starts with 10.0g grams of Uranium -238 how much would remain after 18.0 billion years?

• (4 half-lives)= 10.0g x(1/2)x(1/2)x(1/2)x(1/2) = 0.625g
• 18.0BY/4.51BY = 4
• 10.0g (0 half-lives)
• (1 half-life) = 10.0g x(1/2) = 5.0g
• (2 half-lives)= 10.0g x(1/2)x(1/2) = 2.5g

Iron – 59 beta decays with a half-life of 45 days. Determine how old a sample is with 50.0 g of Iron – 59 and 150.0 g of Cobalt – 59.

• 0 days (0 half-lives) 50.0g Parent + 150.0g Daughter = 200.0g (starting amount)
• 45 days (1 half-life) 200.0gx(1/2) = 100.0g
• 90 days (2 half-life) 200.0gx(1/2)x(1/2) = 50.0g
• 135 days (3 half-lives) 200.0gx(1/2)x(1/2)x(1/2) = 25.0g
• 180 days (4 half-lives) 200.0gx(1/2)x(1/2)x(1/2)x(1/2) = 12.5g