50 points and will give brainliest-- chemistry
some thermodynamic properties of ethanol are listed in the table. thermodynamic propertiesproperty value c (solid) 0.5 j/g °c c (liquid) 1.0 j/g °c c (gas) 2.0 j/g °c melting point −114 °c boiling point 78 °c how much heat is released when 50.0 g of ethanol cools from 90 °c to 79 °c?
1,200 j
1,100 j
600 j
550 j

1,100 J.

Explanation:

Q = m.c.ΔT.

where, Q is the amount of heat released from ethanol cooling,

m is the mass of ethanol (m = 50.0 g),

c is the specific heat of ethanol in the gas phase, since the T is cooled above the boiling point (c = 2.0 J/g °C),

ΔT is the temperature difference (final T - initial T) (ΔT = 79.0 °C – 90.0 °C = - 11.0 °C).

∴ Q = m.c.ΔT = (50.0 g)(2.0 J/g °C)(- 11.0 °C) = - 1100 J.

The system releases 1100 J.

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