Find the number of atoms in 0.470 g of ca (20ca40 and 1 amu = 1.66 x 10-24 g) (you can also use the avogadro’s number 6.022 x 1023).

In 0.470 grams of Calcium, there are 7.05 * 10^21 Ca atoms

Explanation:

Step 1: Data given

We have 0.470 grams of Calcium (Ca)

Calcium has a molar mass of 40.08 amu

Avogadro's number, is the number of units in one mole of any substance and is equal to 6.022 * 10^23

Step 2: Calculate number of moles of Calcum

Number of moles of calcium = mass of Calcium / Molar mass of calcium

Number of moles of calcium = 0.470 grams / 40.08 g/mole = 0.0117 moles

Step 3 : Calculate number of atoms

Since the Avogadro's number says that there are 6.022 *10^23 atoms in 1 mole

This means that in 0.0117 moles of Calcium, we have 0.0117 * 6.022 *10^23 = 7.05 * 10^21 atoms

In 0.470 grams of Calcium, there are 7.05 * 10^21 Ca atoms

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

points

explanation: