Is the earth getting hotter

Lt takes 4 hr 39 min for a 2.00-mg sample of radium-230 to decay to 0.25 mg. what is the half-life of radium-230?

Rufina [12.5K]

Radioactive decay => C = Co { e ^ (- kt) |

Data:

Co = 2.00 mg
C = 0.25 mg
t = 4 hr 39 min

Time conversion: 4 hr 39 min = 4.65 hr

1) Replace the data in the equation to find k

C = Co { e ^ (-kt) } => C / Co = e ^ (-kt) => -kt = ln { C / Co} => kt = ln {Co / C}

=> k = ln {Co / C} / t = ln {2.00mg / 0.25mg} / 4.65 hr = 0.44719

2) Use C / Co = 1/2 to find the hallf-life

C / Co = e ^ (-kt) => -kt = ln (C / Co)

=> -kt = ln (1/2) => kt = ln(2) => t = ln (2) / k

t = ln(2) / 0.44719 = 1.55 hr.

Answer: 1.55 hr

6 0

4 years ago

A student is quickly pipetting 129ul water and observes many bubbles in the tip. You as the second student demonstrate the corre

KonstantinChe [14]

Push the pushbutton to the first stop before inserting the tip into the solution, and then put the tip in the solution tube.

6 0

4 years ago

The [OH-] of a solution is 7.89 10^-12 M. What is the pH of the solution? it acidic or basic? *

kompoz [17]

Answer: pH = 2,897 , basic $[H+][OH-] = 10^{-14} ==> [H+] = \frac{10^{-14}}{7,89*10^{-12} } =\frac{1}{789} \\pH= -lg([H+]) = 2,897 \\pH basic$

Explanation:

6 0

3 years ago

Need help ASAP plzzzzzz

oee [108]

Answer:

Biodiesel has a higher oxygen content (usually 10 to 12 percent) than petroleum diesel. ... Biodiesel is more chemically active as a solvent than petroleum diesel. As a result, it can be more aggressive to some materials that are normally considered safe for diesel fuel. Biodiesel is much less toxic than petroleum diesel.

5 0

3 years ago

A compound was decomposed and determined to be 51.27 % C, 7.75 % H and 40.98 % O by mass. What is the subscript for H in the emp

Vlad [161]

The subscript for H in the empirical formula for this compound is 3.

There are 3 steps involved in the construction of empirical formula.

Calculation of empirical formula is as under as ...

Step 1: Divide the % of each atoms which their atomic weights.

C = 51.27 / 12 = 4.27

H = 7.75 / 1 = 7.75

O = 40.98 / 16 =2.56

Step 2 : Divide all the answers with the smallest answer to get the subscripts for empirical formula.

C = 4.27/ 2.56 ≈ 2

H = 7.75/ 2.56 ≈ 3

O = 2.56 /2.56 = 1

Step 3: Construction of empirical formula by putting subscripts calculated in step 2.

Empirical formula form given data = $C_{2} H_{3} O_{1}$

Thus , subscript for H in the empirical formula for this compound is 3.

Learn more about empirical formula here..

brainly.com/question/13058832

#SPJ4

4 0

2 years ago