Question

1.Aluminum powder burns in the are with a dazzling to produce aluminum oxide
4Al(s) + 3O2(g) ----> 2Al2O3(s)
How many moles of O2 are consumed when .770 mol of aluminum burns?

2. How many molecules are contained in .0172 kg of C2H4

3. A piece of uranium with a denisty of 18.9(g/cm^3) and a mass of 281 grams is fired at a velocity of 385 m/s. Estimate the wavelength of the projectile

Answer 1

Answer – 1) Given, reaction 4Al(s) + 3O₂(g) ----> 2Al₂O₃(s)

Moles of Al = 0.770 moles

From the given balanced equation

4 moles of Al = 3 moles of O₂

So, 0.770 moles of Al = ?

= 0.578 moles of O₂

So, 0.578 moles of O2 are consumed when .770 mol of aluminum burns.

2) Given, mass of C₂H₄ = 0.0172 kg

First we need to converted mass kg to g

We know,

1 kg = 1000 g

So, 0.0172 kg = ?

= 17.2 g

Now we need to calculate the mole of C₂H₄

Moles of C₂H₄ = 17.2 g / 28.05 g.mol^-1

                        = 0.613 moles

Now we know

1 mole = 6.023*10²³ molecules

So, 0.613 moles = ?

= 3.69*10²³ molecules of C₂H₄

3) Given, density = 18.9 g/cm³, mass = 281 g

Velocity = 385 m/s

We need to convert the given mass g to kg

We know

1 g = 0.001 kg

281 g = ?

= 0.281 kg

We know the De Broglie wavelength formula

λ = h/mv

   = 6.626*10^-34 J.s / 0.281 kg *385 m.s^-1

   = 6.16*10^-36 m

wavelength of the projectile is 6.16*10^-36 m