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bulgar [2K]
3 years ago
5

Cobalt-60, with a half-life of 5.0 days, is used in cancer radiation treatments. A hospital purchases a 30.0g supply of it and s

tores it on a shelf in a closet. The next time a hospital worker grabs the bottle, though, they find that it only contains 3.75 g remaining! Assuming the bottle had never been opened, how long was the bottle sitting on the shelf before the worked grabbed it?
Chemistry
1 answer:
Rudik [331]3 years ago
8 0

Answer:

Bottle is sitting on the shelf for 15 days.

Explanation:

Given data:

Co-60 half life = 5 days

Total amount = 30.0 g

Amount left = 3.75 g

Time taken = ?

Solution:

AT time zero = 30 g

AT first half life= 30g /2 = 15 g

At 2nd half life = 15 g/ 2 = 7.5 g

At 3rd half life = 7.5 g/2 = 3.75 g

Now we will calculate the sitting time of bottle.

Half life = Time taken / number of half lives

3× 5 days = time taken

Time taken = 15 days

Bottle is sitting on the shelf for 15 days.

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What was the purpose of putting distilled water in the blank cuvette? if your unknown used ethanol as the base solvent, what wou
Margaret [11]

The purpose of using distilled water in the cuvette of the spectrophotometer is to calibrate the instrument. It is generally considered that distilled water shows zero absorbance and 100 % transmittance. So, to zero out the absorbance of compounds other than the analyte being determined, distilled water is used as a blank.

If the unknown being determined is prepared using ethanol as the base solution, the blank used must be ethanol. This is because absorbance if any from the solvent, ethanol must be zeroed out as when the measurement of the actual unknown is being made, the absorbance of the solvent does not interfere.

7 0
3 years ago
The enthalpy of a pure liquid at 75oC is 100 J/mol. The enthalpy of the pure vapor of that substance at 75oC is 1000 J/mol. What
pentagon [3]

Answer:

900 J/mol

Explanation:

Data provided:

Enthalpy of the pure liquid at 75° C = 100 J/mol

Enthalpy of the pure vapor at 75° C = 1000 J/mol

Now,

the heat of vaporization is the the change in enthalpy from the liquid state to the vapor stage.

Thus, mathematically,

The heat of vaporization at 75° C

=  Enthalpy of the pure vapor at 75° C - Enthalpy of the pure liquid at 75° C

on substituting the values, we get

The heat of vaporization at 75° C = 1000 J/mol - 100 J/mol

or

The heat of vaporization at 75° C = 900 J/mol

8 0
3 years ago
Which of the following statements is true?
vaieri [72.5K]
I think D?? I apologize if not-check in other answers to be sure ^^
7 0
3 years ago
Read 2 more answers
You are in charge of inflating balloons for a parade. When you inflate the balloons in the morning, It will be 15 degrees Celsiu
tatiyna

Answer:

so you answer would be B

Explanation:

well what you would do is add 15+25=40  and what they are asking is whay are the degrees in the balloon so you would have B as your answer

hoped i helped have a great weekend

8 0
3 years ago
HELP ME PLEASE ILL MARK U THE BRAINLIEST
ElenaW [278]

Answer:

pentene-alkanes-C5H10

octane-alkanes-C 8H 18

butene-alkene-c4h8

decane-alkane-c10h22

6 0
3 years ago
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