please check my answers for the following questions.
1) when a measurement that has six significant digits is divided by a measurement that has three significant digits, how many significant digits should the answer have?
ANSWER: 2
2) How many hydrogen atoms are in 5 molecules of isopropyl alcohol, C3H7O?
ANSWER: 35
3) How many moles of SO3 are in 2.4 x 10^24 molecules of SO3
ANSWER: 4.0
Number one is incorrect. Three is the answer: in muliplication and division, the answer is limited to the number of significant digits of the least number. In this case, three is the limit in the denominator.
The chemical formula for aspirin is C9H8O4 What is the mass of 0.40 mol of aspirin?
45g
10.8g
160g
72g
To find the mass of 0.40 mol of aspirin (C9H8O4), you need to multiply the molar mass of aspirin by the number of moles. The molar mass of aspirin can be calculated by adding up the atomic masses of carbon (C), hydrogen (H), and oxygen (O).
C9H8O4 molar mass:
(9 x atomic mass of carbon) + (8 x atomic mass of hydrogen) + (4 x atomic mass of oxygen)
(9 x 12.01 g/mol) + (8 x 1.01 g/mol) + (4 x 16.00 g/mol) = 180.16 g/mol
Now, you can calculate the mass by multiplying the molar mass by the number of moles:
0.40 mol x 180.16 g/mol = 72.06 g
Therefore, the mass of 0.40 mol of aspirin is approximately 72.06 grams.
To find the mass of a substance using its chemical formula and the number of moles, you need to calculate the molar mass of the substance and then multiply it by the number of moles.
To calculate the molar mass of aspirin (C9H8O4), you need to find the atomic masses of each element in the formula from the periodic table and add them up.
C: atomic mass = 12.01 g/mol
H: atomic mass = 1.01 g/mol
O: atomic mass = 16.00 g/mol
Now, calculate the molar mass of aspirin:
(9 * 12.01 g/mol) + (8 * 1.01 g/mol) + (4 * 16.00 g/mol) = 180.16 g/mol
Next, multiply the molar mass by the number of moles (0.40 mol):
0.40 mol * 180.16 g/mol = 72.06 g
Therefore, the mass of 0.40 mol of aspirin is approximately 72.06 grams.
So the correct answer is 72g.