# Convert 50g of calcium carbonate, CaCO3, into moles

Moles  =  0.5 mol

Solution:

Moles is related to mass as follow,

Moles  =  Mass / M.mass   ----- (1)

Where;
Mass  =  50 g

M.mass  =  Ca (40) + C (12) + O₃ (16)₃  =  100 g/mol

Putting values in equation 1,

Moles  =  50 g ÷ 100 g.mol⁻¹

Moles  =  0.5 mol

## Related Questions

According to the equation below, which of the following will cause the concentration of H2SO4 to increase? 2NaHCO3 (s) + H2SO4 (aq) ⇄ Na2SO4 (aq) + 2H2O (l) + 2CO2 (g) View Available Hint(s) According to the equation below, which of the following will cause the concentration of H2SO4 to increase? 2NaHCO3 (s) + H2SO4 (aq) ⇄ Na2SO4 (aq) + 2H2O (l) + 2CO2 (g) addition of some NaHCO3 (s) addition of some Na2SO4 (aq) removal of some H2O (l) removal of some CO2 (g)

Explanation:

2NaHCO₃ (s) + H₂SO₄ (aq) ⇄ Na₂SO₄ (aq) + 2H₂O (l) + 2CO₂ (g)

According to the Le Chatelier's principle, the addition of Na₂SO₄ to the reaction would lead to shift to the direction of the reaction that consumes Na₂SO₄, in order to reestablish equilibrium. Since the reaction that consumes Na₂SO₄ is the reaction that produces H₂SO₄, the concentration of H₂SO₄ would increase.

What is the atomic number of an element containing 12 neutrons and having a mass number of 24

The element is magnesium, its atomic number is 12.

Calculate the molality of a 35.4 % (by mass) aqueous solution of phosphoric acid (H3PO4) (35.4 % means 35.4 g of H3PO4in 100 g of solution)

3.6124 m/kg

Explanation:

Molality is calculated as moles of solute (mol) divided by kilogram of solvent (kg). Here, we can find these numbers by using the 35.4%, which gives us  35.4 g of H3PO4 and 100 g of solution to work with.

To go from grams to moles for the phosphoric acid, you need to find the molar mass of the compound or element and divide the grams of the compound or element by that molar mass.

Here, the molar mass for phosphoric acid is 97.9952 g/mol. The equation would look like this:

35.4 g x 1 mol / 97.9952 g = 0.3612422 mol

Next, the 100 g of solvent can easily be converted to 0.1 kg of solvent.

To find the molality, divide the moles of solute and kilograms of solution.

0.3612422 mol / 0.1 kg = 3.6124 m/kg

A biochemist studying breakdown of the insecticide DDT finds that it decomposes by a first-order reaction with a half-life of 12.0 yr. How long does it take DDT in a soil sample to decompose from 809 ppbm to 10.0 ppbm (parts per billion by mass)

76.0 years

Explanation:

Step 1: Given data

• Half-life (t1/2): 12.0 y
• Initial concentration of DDT ([A]₀): 809 ppbm
• Final concentration of DDT ([A]): 10.0 ppbm
• Time elapsed (t): ?

Step 2: Calculate the rate constant (k)

We will use the following expression.

k = ln 2/ t1/2 = ln 2 / 12.0 y = 0.0578 y⁻¹

Step 3: Calculate the time elapsed

For a first-reaction order, we will use the following equation.

ln [A]/[A]₀ = -k × t

t = ln [A]/[A]₀ / (-k)

t = (ln 10.0 ppbm/809 ppbm) / (-0.0578 y⁻¹)

t = 76.0 y

When the reaction mixture is worked-up, it is first washed three times with 5% sodium bicarbonate, and then with a saturated nacl solution. explain why?