The concentration (M) of an aqueous methanol produced when 0.200 L of a 2.00 M solution was diluted to 0.800 L is . 0.800 0.200 0.500 0.400 8.00

0.5M

Explanation:

Dilution formula is often used to determine the volume or concentration needed to dilute a solution inorder to achieve the required concentration.

Dilution formula is given as

C₁ × V₁ = C₂ × V₂

C₁ = Initial concentration of methanol = 2.00M

V₁ = Initial volume of methanol=0.200L

C₂ = Final Concentration of methanol = ?

V₂ = Final Volume of methanol = 0.800L

therefore, C₁ × V₁ = C₂ × V₂

2 × 0.2 = C₂ × 0.8

0.4= C₂ × 0.8

C₂ = 0.4/0.8

C₂ = 0.5M

the concentration produce is 0.5M

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol