#1) Complete the following calculation by providing the correctly rounded answer in SI Units: 6.25 g divided by 8.25 g/mol
#2)You are using a scale that has an accuracy of 0.01g. Suppose you have been told that one raisin has a mass of 1.011 g and you measure the other 9 raisins at a mass of 1.01 g each. What would be the mass of 10 raisins? State your answer to the correct number of significant digits.
Divide 6.25/8.25 = ?? There are three significant figures in each; therefore, you are allowed three in the final answer by the multiplication/division rules.
#2. I can interpret the question two ways. IF I KNOW, because someone told me, that EACH raisin had a mass of 1.011 grams, then I wouldn't need a balance (I don't call them scales). I would simply multiply 1.011 x 10 = 10.11 grams.
BUT, if only one raisin has a mass of 1.011 g (and I know that's exact), then I add
1.01 +
1.01 +
1.01 +
etc 9 times and the answer is
9.09 grams for the 9 raisins. Then if I add
9.09 + (the 1.01 added 9 times and accurate to the hundredths place. +
1.011 (accurate to the thousandths place.
------
10.101 grams
In addition/subtraction, the number of s.f. is determined by the digits to the right of the decimal point. In this case, the accuracy is to the hundredths place; therefore, the total should be rounded to 10.10 (dropping the last 1 of the 10.101).
Check my thinking. I think the problem was meant to be interpreted the latter way.
Thank-you, That's what I thought to for #2...
#1) To calculate the result, we need to divide 6.25 grams by 8.25 grams per mole. The unit "g/mol" is molar mass, which represents the mass of one mole of a substance.
To get the answer, we divide the given mass (6.25 g) by the molar mass (8.25 g/mol):
6.25 g / 8.25 g/mol = 0.7575757575757576 mol
Now, let's round the answer to the desired number of significant figures. Since the given quantities have four significant digits, we will round the answer to four significant figures as well. Therefore, the rounded answer is:
0.7576 mol
#2) The problem states that the scale has an accuracy of 0.01 grams. This means that any measurements made on this scale will have an uncertainty of ±0.01 grams.
Given that one raisin has a mass of 1.011 grams and the other nine raisins have a mass of 1.01 grams each, we can calculate the total mass of ten raisins by adding the individual masses:
(1.011 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g + 1.01 g) = 10.061 g
Now, let's consider the significant figures. The measurement of the first raisin has four significant figures (1.011 g), and the measurements of the other nine raisins have three significant figures (1.01 g each). Since the addition involves both measurements with four significant figures and measurements with three significant figures, we should round our final answer to the least precise measurement. In this case, the measurements with three significant figures are less precise.
Therefore, rounding the final answer to the correct number of significant figures (three significant figures), the mass of ten raisins is:
10.1 g