Please help I’m doing a quiz right now How many atoms are in 21.26 grams of copper?

22

g Cu

contains

2.1

×

10

23

atoms of Cu.

Explanation:

In order to solve this problem, you need to determine the molar mass of copper, which is the mass of one mole of copper. The molar mass of copper is its atomic weight on the periodic table in g/mol, and is

63.546g/mol

. You also need to know that one mole of copper contains

6.022

×

10

23

atoms of copper. With this information you can solve this problem using dimensional analysis. You will convert given mass to moles, and moles to atoms.

22

g Cu

×

1

mol Cu

63.546

g Cu

×

6.022

×

10

23

atoms Cu

1

mol Cu

=

2.1

×

10

23

atoms Cu

The moles and grams cancel, leaving number of atoms.

22

g Cu

contains

2.1

×

10

23

atoms of Cu.

Explanation:

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answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.