A student has a 1g sample of each of the following compounds: NaCl, KBr, and KCL Which of the following lists the samples in ord
1 answer:
Given :
A student has a 1 g sample of each of the following compounds: NaCl, KBr, and KCl.
To Find :
The samples in order of increasing number of moles in the sample.
Solution :
Molecular mass of NaCl, KBr, and KCl is 58.5 g/mol , 119 g/mol and
74.5 g/mol respectively .
Moles of NaCl , .
Moles of KBr , .
Moles of KCl , .
The order of moles in increasing order is :
KBr , KCl and NaCl .
Hence , this is the required solution .
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Answer:
Explanation:
The half-life of K-40 (1.3 billion years) is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction
<u>half-lives</u> <u> t/yr </u> <u>Remaining</u>
0 0 1
1 1.3 billion ½
2 2.6 ¼
3 3.9 ⅛
We see that after 2 half-lives, ¼ of the original mass remains.
Conversely, if two half-lives have passed, the original mass must have been four times the mass we have now.
Original mass = 4 × 2.10 g =