Answer: It is important to wet the filter paper in the Buchner funnel first with cold re crystallization solvent before the re crystallization mixture being filtered to minimize gaps around the edges of the filter paper which can prevent mechanical impurities from passing through. This gives better filtration where most impurities can be filtered. Furthermore, it provides good vacuum.
<span> POCl3 is the correct way to write the chemical formula for this compound</span>
Among the choices, bromine exists as liquid under standard temperature and pressure conditions. Unlike other diatomic molecules which exist as gases, due to its heavy molecular weight, it exists as solid. Francium and cesium are solids while iodine is gas.Answer is 1.
<h2>Steps:</h2>
- Remember that Density = mass/volume, or D = m/v
So firstly, we have to find the volume of the rock. To do this, we need to subtract the volume of water A from the volume of the water B. In this case:
- Water A = 30 mL
- Water B = 40 mL
- 40 mL - 30 mL = 10 mL
<u>The volume of the rock is 10 mL.</u>
Now that we have the volume, we can plug that and the density of the rock into the density equation to solve for the mass.

For this, multiply both sides by 10:

<h2>Answer:</h2>
<u>Rounding to the tenths place, the mass of the rock is 36.8 g, or C.</u>