How many total atoms are in 0.920 g of p2o5?

Given:

0.920 g of P2O5

Required:

Total atoms

Solution:

The molar mass of P2O5 is 284 grams per mole.

0.920 grams / 284 grams per mole of P2O5 = 3.24 x 10^-3 mole P2O5

Using Avogadro’s law where 1 mole of substance equals 6.023 x 10^23 atoms

3.24 x 10^-3 mole P2O5 (6.023 x 10^23 atoms/mole) = 1.95 x 10^21 atoms P2O5

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j