If 58.67g of mercuric oxide were completely decomposed to generate 54.34 g of mercury how many grams of oxygen should have been produced

4.33g

Explanation:

The reaction equation is given as:

        2HgO → 2Hg + O₂

Given parameters:

Mass of HgO = 58.67g

Mass of Hg produced = 54.34g

Unknown:

Mass of oxygen produced = ?

Solution

From the reaction equation, using the mole concept, it is possible to determine the mass of oxygen gas produced.

To do this, we first determine the molar composition of the mass of the given mercury oxide. Then we use the balanced reaction equation to determine the mass of oxygen produced:

Number of moles of HgO =

Molar mass of HgO = 200.6 + 16 = 216.6gmol⁻¹

Number of moles of HgO = = 0.271mol

From the reaction equation, we know that:

           2moles of HgO produced 1 mole of O₂

           0.271moles of HgO would also produce, 0.136mol

Therefore, mass of O₂ gas produced = number of moles of O₂ x molar mass

    Molar mass of O₂ = 16x2 = 32gmol⁻¹

Mass of O₂ gas = 0.136 x 32 = 4.33g

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