Okay this is the question! What is the result of the following calculation to the correct number of significant figures?
(6.266 - 6.261) / 522.0 = ?
Well I did it but I got it wrong.
=0.00000957854
This is what I got so I moved the decimal 6 times to the right (so the right means the power will be negative) I ended up getting 9.5 x 10^-6
But it was wrong so I did it again so I checked the right answer and it said it was 1 x 10^-5 so after this I tried to figure out how in the world it was that answer so this is what I thought please tell me if I'm right or wrong!!!
0.00000957854
moved the decimal to the right 5 times getting .957854 rounding to 1
so...
1 x 10^-5
okay i'm confused as why it isn't 9.5, but it is .95 rounded to 1
I'm thinking it is because the denominator is 522.0? Please explain to me I highly appreciate ittt!!! :D
Can someone help me with my chem homework?
2018-01-26 8:16 pm
回答 (3)
2018-01-26 9:23 pm
✔ 最佳答案
(6.266 - 6.261) / 522.00.005 / 552 = 0.0000096 rounded to 0.00001
the subtraction reduces the number of sign. digits to 1
2018-01-26 8:30 pm
(6.266 - 6.261) / 522.0
= 0.005 / 522.0
= 0.95795 × 10⁻⁵
= 1 × 10⁻⁵
= 0.005 / 522.0
= 0.95795 × 10⁻⁵
= 1 × 10⁻⁵
2018-01-26 9:34 pm
The trick I use is to add or subtract a 5 after the last digit of each number. That's the basic uncertainly in each number.
So then I do (6.2665-6.2605) / 521.95 = 11.49535 x 10^-6.
Compare with the "exact" answer of 9.57854 x 10^-6, the difference is 1.91681 x 10^-6.
Then round so that the difference is only two digits.
The answer is (9.6 +/- 1.9) x 10^-6.
If you round so that the difference is only one digit, then the answer is (10 +/- 2) x 10^-6. But most scientists prefer to round the difference to two digits. Also notice that is is often preferred to use powers that are multiples of 3, such as 10^-3, 10^-6, 10^-12, etc.
So then I do (6.2665-6.2605) / 521.95 = 11.49535 x 10^-6.
Compare with the "exact" answer of 9.57854 x 10^-6, the difference is 1.91681 x 10^-6.
Then round so that the difference is only two digits.
The answer is (9.6 +/- 1.9) x 10^-6.
If you round so that the difference is only one digit, then the answer is (10 +/- 2) x 10^-6. But most scientists prefer to round the difference to two digits. Also notice that is is often preferred to use powers that are multiples of 3, such as 10^-3, 10^-6, 10^-12, etc.
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