A7.300 gram sample of aluminum was quantitatively combined with a sample of selenium to form a compound. the compound weighed 39.35 grams. what is the empirical formula for this compound?

The empirical formula is Al2Se3  

Explanation:

Step 1: Data given

Mass of the sample of aluminium = 7.300 grams

Mass of the compound = 39.35 grams

Molar mass of aluminium = 26.98 g/mol

Molar mass of selenium = 78.96 g/mol

Step 2: Calculate mass of selenium

Mass of selenium = mass of compound - mass of aluminium

Mass of selenium = 39.35 - 7.3 = 32.05 grams

Step 3: Calculate moles of Al

Moles Al = Mass Al/ Molar mass Al

Moles Al = 7.300 grams / 26.98 g/mol

Moles Al = 0.2706 moles

Step 4: Calculate moles of Se

Moles Se = Mass Se / Molar mass Se

Moles Se =32.05 g / 78.96 g/mol

Moles Se = 0.4059 moles

Step 5: Divide through the smallest amount of mol

Aluminium: 0.2706 / 0.2706 = 1

Selenium: 0.4059/0.2706 = 1.5

This means for each mol aluminium, we have 1.5 moles of selenium

For each 2 moles of aluminium, we have 3 moles of selenium

The empirical formula is Al2Se3  

This is aluminium(III) selenide.

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.