2) you are trying to determine a tlc solvent system which will separate the compounds x, y, and z. you ran the compounds on a tlc plate using hexanes/ethyl acetate 95: 5 as the eluting solvent and obtained the chromatogram below. how could you change the solvent system to give better separation of these three compounds?

Answer is in the explanation.

Explanation:

Thin layer chromatography is a chromatographic technique used to separate the components of a mixture using a thin stationary phase supported by an inert backing and a mobile phase. The separation principle is in the different affinities between the components of the mixture and the stationary or mobile phase.

The affinity in mobile phase could be improved changing the polarity of this phase. In this case, you could change proportion of hexane/ethyl acetate to change polarity of mobile phase and the affinity of the different compounds to mobile or stationary phase.

I hope it helps!

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