When potassium metal is placed in water, a large amount of energy is released as potassium hydroxide and hydrogen gas are produced in the reaction 2k(s) + 2h2o(l) → 2koh(aq) + h2(g). your lab partner says this is a redox reaction and a combustion reaction. do you agree? defend your answer by explaining whether or not it meets the requirements of each type of reaction.

The given reaction redox reaction not a combustion reaction.

Explanation:

Redox Reaction is defined chemical reaction in which oxidation and reduction takes place simultaneously. In Oxidation addition of oxygen occurs and in reduction addition of hydrogen occurs.

Potassium is getting oxidized by addition of oxygen.

Water us reduced to hydrogen gas by removal of oxygen

Combustion reaction is defined as chemical reaction in which burning of a chemical compound or element takes place in presence of oxygen occurs.

In the given reaction, oxygen molecule is absent which means this reaction is not combustion reaction.

Hence ,the given reaction redox reaction not a combustion reaction.

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