Could you please tell me if these are right?
How many moles are in the following.
A.) 80.0 g of NaOH I got 2.0 moles.
B.) 12.0 g of Ca(OH)2 I got 0.16 moles.
Write the simplest formula for each of the following compounds.
A.) 0.200 mole Al and 0.600 Cl. I got AlCl3
B.) 0.080 mole Ba, 0.080 mole S, 0.320 mole O. I got BaSO4
You threw away two perfectly good numbers for the first two.
80.0/39.997 = 2.000 which rounds to 2.00 to three significant figures (you are allowed 3 from the 80.0).
12.0/74.093 = 0.16196 which rounds to 0.162 to three s.f. (3 s.f. allowed by the 12.0)
The other two are ok.
hhj
A.) To determine the number of moles in 80.0 g of NaOH, we need to use the molar mass of NaOH. The molar mass of NaOH is:
Na: 22.99 g/mol
O: 16.00 g/mol
H: 1.01 g/mol
Adding them together gives us:
22.99 g/mol + 16.00 g/mol + 1.01 g/mol = 40.00 g/mol
To find the number of moles, we divide the given mass (80.0 g) by the molar mass (40.00 g/mol):
80.0 g / 40.00 g/mol = 2.0 moles
So, your answer of 2.0 moles for 80.0 g of NaOH is correct.
B.) To determine the number of moles in 12.0 g of Ca(OH)2, we follow the same process. The molar mass of Ca(OH)2 is:
Ca: 40.08 g/mol
O: 16.00 g/mol
H: 1.01 g/mol
Adding them together gives us:
40.08 g/mol + (16.00 g/mol x 2) + (1.01 g/mol x 2) = 74.08 g/mol
To find the number of moles, we divide the given mass (12.0 g) by the molar mass (74.08 g/mol):
12.0 g / 74.08 g/mol = 0.1618 moles (rounded to 0.16 moles)
So, your answer of 0.16 moles for 12.0 g of Ca(OH)2 is correct.
For writing the simplest formula:
A.) Given 0.200 mole Al and 0.600 mole Cl, we need to determine the ratio of Al to Cl.
Dividing the given moles by the smallest value (0.200 moles) gives us:
0.200 moles Al / 0.200 moles = 1 Al
0.600 moles Cl / 0.200 moles = 3 Cl
So, the simplest formula for this compound is AlCl3.
B.) Given 0.080 mole Ba, 0.080 mole S, and 0.320 mole O, we need to determine the ratio of each element.
Dividing the given moles by the smallest value (0.080 moles) gives us:
0.080 moles Ba / 0.080 moles = 1 Ba
0.080 moles S / 0.080 moles = 1 S
0.320 moles O / 0.080 moles = 4 O
So, the simplest formula for this compound is BaSO4.
To determine the number of moles in a given mass of a substance, you need to use the formula:
moles = mass / molar mass
Let's calculate the moles for each of the given substances:
A.) 80.0 g of NaOH
The molar mass of NaOH is: 22.99 g/mol (for Na) + 16.00 g/mol (for O) + 1.01 g/mol (for H) = 39.99 g/mol
Using the formula, we can calculate:
moles = 80.0 g / 39.99 g/mol ≈ 2.00 moles
So, your answer of 2.0 moles is correct.
B.) 12.0 g of Ca(OH)2
The molar mass of Ca(OH)2 is: 40.08 g/mol (for Ca) + 16.00 g/mol (for O) + 1.01 g/mol (for H) times 2 (since there are 2 hydroxide groups in the formula) = 74.10 g/mol
Using the formula, we can calculate:
moles = 12.0 g / 74.10 g/mol ≈ 0.162 moles
So, the correct answer is approximately 0.16 moles, as you mentioned.
Now, let's move to determining the simplest formula for each compound:
A.) 0.200 mole Al and 0.600 Cl
First, we need to find the simplest ratio between aluminum (Al) and chlorine (Cl). From the mole amounts given, it can be observed that the ratio is Al:Cl = 1:3. This means that there are 3 moles of chlorine for every 1 mole of aluminum.
Hence, the simplest formula for this compound is AlCl3.
B.) 0.080 mole Ba, 0.080 mole S, 0.320 mole O
Following the same procedure as in the previous example, the ratio between barium (Ba), sulfur (S), and oxygen (O) is Ba:S:O = 1:1:4. Therefore, the simplest formula for this compound is BaSO4.
Your answers for both parts are correct. Well done!