"a compound containing only carbon and hydrogen and which has only single bonds between atoms is classified as an"

If 12.5 grams of the original sample of cesium-137 remained after 90.6 years, what was the mass of the original sample?

myrzilka [38]

Answer:

Mass of original sample = 100 g

Explanation:

Half life of cesium-137 = 30.17 years

$t_{1/2}=\frac {ln\ 2}{k}$

Where, k is rate constant

So,

$k=\frac{\ln2}{t_{1/2}}$

$k=\frac{\ln2}{30.17}\ year^{-1}$

The rate constant, k = 0.02297 year⁻¹

Time = 90.6 years

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Initial concentration $[A_0]$ = ?

Final concentration $[A_t]$ = 12.5 grams

Applying in the above equation, we get that:-

$12.5\ g=[A_0]e^{-0.02297\times 90.6}$

$[A_0]=\frac{12.5}{e^{-0.02297\times 90.6}}\ g=100\ g$

<u>Mass of original sample = 100 g</u>

8 0

3 years ago

15.0 g of Fe and 25.0 g of sand are added to 250.0 g of water. a. Determine the percent mass of Fe, sand, and water in the mixtu

lana [24]

Answer:

A. percentage mass of iron = 5.17%

percentage mass of sand = 8.62%

percentage mass of water = 86.205%

B. (Iron + sand + water) -------> ( iron + sand) ------> sand

C. The step of separation of iron and sand

Explanation:

A. Percentage mass of the mixtures:

Total mass of mixture = (15.0 + 25.0 + 250.0) g =290.0 g

percentage mass of iron = 15/290 * 100% = 5.17%

percentage mass of sand = 25/290 * 100% = 8.62%

percentage mass of water = 250/290 * 100% = 86.205%

B. Flow chart of separation procedure

(Iron + sand + water) -------> separation by filtration using filter paper and funnel to remove water --------> ( iron + sand) -----------> separation using magnet to remove iron ------> sand

C. The step of separation of iron and sand by magnetization of iron will have the highest amount of error because during the process, some iron particles may not readily be attracted to the magnet as they may have become interlaced in-between sand grains. Also, some sand particle may also be attracted to the magnet as they are are borne on iron particles.

5 0

3 years ago

A certain protein was found to contain 0.292% manganese by mass. Determine the minimum molecular mass of the protein.

Lisa [10]

$55u \ \ \ \ \ \ \Rightarrow \ \ \ \ \ 0,292\%\\
x \ \ \ \ \ \ \ \ \ \Rightarrow \ \ \ \ \ 100\%\\\\
x = \frac{55u*100\%}{0,292\%}\approx18835,62u$

4 0

3 years ago

The equation 2al(s) + 3br2(l) → 2albr3(s) is a(n) ______________ reaction.

Svetach [21]

Combination
Hope this helps :)

7 0

3 years ago

What is the molarity of 0.26 mol of H2SO4 dissolved in 0.3 L of solution? *

irina1246 [14]

Answer:

A

Explanation:

molarity=moles of solute/liter of solution

molarity=0.26/0.3

molarity=0.87molar

7 0

3 years ago