Answer:

Explanation:
We want to convert from moles to grams, so we must use the molar mass.
<h3>1. Molar Mass</h3>
The molar mass is the mass of 1 mole of a substance. It is the same as the atomic masses on the Periodic Table, but the units are grams per mole (g/mol) instead of atomic mass units (amu).
We are given the compound PI₃ or phosphorus triiodide. Look up the molar masses of the individual elements.
- Phosphorus (P): 30.973762 g/mol
- Iodine (I): 126.9045 g/mol
Note that there is a subscript of 3 after the I in the formula. This means there are 3 moles of iodine in 1 mole of the compound PI₃. We should multiply iodine's molar mass by 3, then add phosphorus's molar mass.
- I₃: 126.9045 * 3=380.7135 g/mol
- PI₃: 30.973762 + 380.7135 = 411.687262 g/mol
<h3>2. Convert Moles to Grams</h3>
Use the molar mass as a ratio.

We want to convert 3.14 moles to grams, so we multiply by that value.

The units of moles of PI₃ cancel.


<h3>3. Round</h3>
The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated, that is the tens place.
The 2 in the ones place tells us to leave the 9.

3.14 moles of phosphorous triiodide is approximately equal to <u>1290 grams of phosphorus triodide.</u>
Answer:
I remember doing this in 7th,
1. D
2. B or D, more leaning on B though
3. A
Answer:
Ca(NO3)2 has the highest boiling point ( option A)
Explanation:
Step 1: Data given
A. 1.25 M Ca(NO3)2
B. 1.25 M KNO3
C. 1.25 M CH3OH
D. 2.50 M C6H12O6
Step 2: Calculate highest boiling point
The boiling point depends on the van't Hoff factor
This shows the particles produced when the substance is dissolved. For non-electrolytes dissolved in water, the van' t Hoff factor is 1.
Ca(NO3)2 → Ca^2+ + 2NO3- → Van't Hoff factor = 3
KNO3 → K+ + NO3- → Van't Hoff factor = 2
CH3OH is a non-elektrolyte → Van't Hoff factor = 1
C6H12O6 is a non-elektrolyte → Van't Hoff factor = 1
Ca(NO3)2 has the highest boiling point
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