Question

# 1. How many ATOMS of boron are present in 8.79 grams of boron trifluoride ?  atoms of...

1. How many ATOMS of boron are present in 8.79 grams of boron trifluoride ?  atoms of boron .

2. How many GRAMS of fluorine are present in 5.10×1022molecules of boron trifluoride ? grams of fluorine .

Boron Trifluoride : BF3.
Molar mass of BF3 : 67.82 g/mol

1. Moles of BF3 in 8.79 g : 8.79 g/ (67.82 g/mol​)
: 0.1296 mole
Now 1 mole of BF3 contains 6.022 x 1023 molecules of BF3.
Therefore, 0.1296 mole​ of BF3 contains = (0.1296 mole​​) x (6.022 x 1023 molecules​/ mole)
= 7.8045 x 1022 molecules of BF3.
Now 1 molecule of BF3 has 1 atom of Boron B, therefore 7.8045 x 1022 molecules of BF3.​ will have 7.8045 x 1022 atoms of Boron.

2.) Determine the moles of BF3 = 5.10 x 1022 molecules/ (6.022 x 1023 molecules/ mole)
= 0.0847 mole BF3.
Now 1 mole of BF3 contains 3 moles Fluorine F. Therefore, 0.0847 mole BF3 will have = 3 x 0.0847 mole F
= 0.2541 mole F
Now, molar mass of fluorine = 19 g/ mol
Grams of fluorine = (0.2541 mole) x (19 g/ mol)
= 4.8279 g

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