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3

The answer is: it depends. Dissolution of a salt implies that the entropy gained exceeds the cost of breaking lattice interactions (the solution enthalpy, assuming it is positive). Electrostatic interactions compete with kT (thermal jostling). Under physiological conditions, long range interactions are strongly screened by intervening solvent molecules and ...


0

The indicator may slowly disappear after the titration because it is reacting with the air. As it reacts with chemicals in the air (CO 2 for example) which causes the indicator to be slowly disappear from the solution.


0

but I am not sure about $\Delta_{mix}V$. [...] I think it should be less than zero because the observed vapour pressure is more than that predicted on the basis of theoretical calculations $\Delta_{mix}V$ refers to the change in the volume of the liquid with mixing, compared to the pure components. The vapour plays no role in this computation. Note also ...


3

In strongly basic solutions, phenolphthalein is converted to its $\ce{In(OH)^3-}$ form, and its pink color undergoes a rather slow fading reaction and becomes completely colorless above $\mathrm{pH}= 13$. wikipedia So the strong alkali is very probable reason, but bleachers or other compounds reacting with phph cannot be eliminated.


0

$$\frac{S +1}{W + S + 1} = 1/3$$ $$\frac{ S + 1}{W+S+2}= 3/10$$ $$S +1=\frac {W + S + 1}3$$ $$S + 1=(W+S+2) \cdot 3/10$$ $$3S +3=W + S + 1$$ $$10S + 10=(W+S+2) \cdot 3$$ $$W=2S +2$$ $$10S + 10=(2S+2+S+2) \cdot 3$$ $$10S + 10=9S+12$$ $$S=2$$ $$W=6$$ The initial concentration is 25 % (w/w).


4

I always suggest students to try Google Scholar (scholar.google.com) when a simple Google search fails. I just searched three keywords : alkali metals ammonia solutions and the third result is highly relevant. When your book talks about "in concentrated solution", it means more alkali metal in liquid ammonia. This paper, which you should search in Google ...


4

Try to get some clay and shake it vigorously with water. Let it settle for a several hours. Test your filter with the supernatant water and collect the filtrate in a very clean glass tumbler. Colloids have an interesting property of scattering light. In a dark room, try to shine light (ordinary flashlight might work or perhaps an ordinary pointer used in ...


-2

remember two solutions of different concentrations are mixed together, the total number of moles of the solution is the sum of the moles of the individual solutions. when you get the sum of the moles, u add their volumes and use those two to determine the new concentration of the solution number of moles= .02*3=.06moles number of moles=.03*5=.015moles ...


0

The vapor pressure of IPA at 2.4 degrees C is 1/4 that of its room temperature value (ref). The viscosity of IPA also increases dramatically as temperature cools to ~0 (ref). Could you simply conduct the evaporation with the same solution but in a colder environment? A normal household fridge should be in the right range for what you're looking for. The ...


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