Present Your Findings 1. Make a graph of the data collected.
a. Label the x-axis as time.
b. Label the y-axis as the number of undecayed atoms.
c. Be sure to title the graph.
d. Turn the graph into your teacher.
2. Write a summary paragraph discussing this experiment and the results. Use the following questions to help guide the
content of your paragraph.
a. What was your hypothesis? According to your data, do you think your hypothesis was correct?
b. What is a half-life?
c. When does a radioactive sample emit the largest number of decay particles? Why is this information important?
(How can it be applied in our world today?)
d. Do you think the shape of the curve on your graph would change if you increased the half-life to 20 seconds?
What does this reveal about radioactive decay?
e. Do you think the shape of the curve on your graph would change if you started with a smaller sample, say 50
atoms (pennies)? What does this reveal about radioactive decay?

To your project!!

Experiment Half-Life

a.My hypothesis is that when we get through 6 half-life’s you will be left with no atoms, and each time the atom number will decrease. Half of my hypothesis was correct whilst the numbers did decrease we, after 6 trials were left with one undecayed atom.

b.what is a half life?

the time required for the decay of one-half of the atoms in a sample of radioactive material

c.When does a radioactive sample emit the largest number of decay particles? when it first starts to decay

Why is this information important? Half-Life and decay is important today because it helps us determine the date of death and birth of ancient mummies.

d.Do you think the shape of the curve on your graph would change if you increased the half-life to 20 seconds? Yes different data would arise and that would change the graph.

What does this reveal about radioactive decay? The longer a material or substance takes to decay the larger the amount of decayed material or substance will come from the substance

e.Do you think the shape of the curve on your graph would change if you started with a smaller sample, say 50 atoms (pennies)? Yes, again different data would arise and that would change the graph.

What does this reveal about radioactive decay? The smaller the sample the quicker it will decay. And the less product that comes from the sample.

Your project is done, it worked for me hope it does for you? DON'T USE THE EXACT SAME WORDS IT'S SUS

here is the graph too!

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol