How many nickel atoms are in a nickel coin with a mass of 3.95g

4.05 × 10²² atoms

Explanation:

Step 1: Given data

Mass of nickel: 3.95 g

Step 2: Calculate the moles corresponding to 3.95 g of nickel

The molar mass of nickel is 58.69 g/mol.

3.95 g × (1 mol/58.69 g) = 0.0673 mol

Step 3: Calculate the atoms in 0.0673 moles of nickel

We will use Avogadro's number: there are 6.02 × 10²³ atoms of nickel in 1 mole of atoms of nickel.

0.0673 mol × (6.02 × 10²³ atoms/1 mol) = 4.05 × 10²² atoms

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol