How many atoms are in 25.00 g of B. 1.393 x 10^24 atoms of B

1.333 x 10^23 atoms of B

2.16 x 10^26 atoms of B

2.17 x 10^24 atoms of B

Explanation:

1. Convert Grams to Moles

Use the molar mass (found on the Periodic Table) to convert from grams to moles.

Use this value as a ratio.

Multiply by the given number of grams.

Flip the ratio so the grams of boron cancel out.

2. Convert Moles to Atoms

We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.

Multiply by the number of moles we calculated.

The moles of boron cancel.

The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.

The 6 tells us to round the 2 to a 3.

25.00 grams of boron is equal to 1.393*10²⁴ atoms.

question: ray weighs 100 kilograms, his wrestling partner, bobby, weighs 50 kilograms. if ray moves at 4 m s , how fast will bobby have to run at him to apply an equal amount of kinetic energy?

answer: 8 m/s he needs to run twice as fast to keep up so he has some work to do

explanation:   if the mass has units of kilograms and the velocity of meters per second, the kinetic energy has units of kilograms-meters squared per second squared.

question answered by

(jacemorris04)