Recent content by DrJohn

If it is not an isolated event, I'd say the question asks if evolution is constantly occurring. So you need to find examples of evolution still happening. EG certain moths or butterflies in the UK turned from white to brown or black due to smoke from trains meaning dark coloured insects were...

Is your question as posted the actual wording of the question you were given? I've seen many questions here which are like a bad summary, missing out key words.

"The now-helpless human race follows its trusted AI leaders down, down, down." The not so helpless humans cut off the power supply going into the AI center. The humans live happily ever after.

Totally agree, but it was almost midnight uk time, I had had some wine, which clearly contained alcohol :biggrin: , and my lady was urging me to come to bed 😚😉😍 . And I thought "spell azeotropic mixture to find graphs for extra info? - nah go to bed". I'd already found articles about ethanol in...

As water is also formed during the fermentation in bread, and has the highest boiling point of the three - water, ethanol, and carbon dioxide - as a guess, perhaps it too is contributing to the bubble size inside the bread, with more of the carbon dioxide and ethanol escaping than the water...

As I said, and as the intro text you quote says, this type of equation is tricky to balance by inspection (looking at it and working through a different set of rules) What purpose do the H+ ions serve? They mop up the O atoms to form water and lead to a balanced final equation! So they need to...

You seem to be forgetting that if you add some acid to pure water, the acid dissociates and increases the amount of H+ ions. This disturbs the equilibrium and some of the H+ ions react with the OH- ions to form some more H2O, until the equilibrium is restored, and satisfies the Kw value. Whether...

So their answer of 0.62M is one of two things. a) Wrong or b) They altered the question to make it slightly different, and forgot to alter the answer. Settle for you got it right!

What we refer to as an H+ ion in solution is more complicated that just an H+ sitting there and not interacting with anything. Slightly more advanced ways of explaining what it is says call it H3O+, but even that is not a full explanation. And if we look at the entire coordination sphere, it...

The H+ is there to mop up the O to give H2O. It results in balancing the equation overall. It accounts for the O in the permanganate ion, as they can't just disappear. By following the steps as written you are able to balance an equation that is trickier to balance by other methods, especially...

"Why can we not put just hydronium ions in pure water?" Because you can't pick up a bucket of just one type of ion.

"Is it possible to make pure water acidic by somehow increasing the concentration of hydronium relative to hydroxide without adding anything else into the water (ie, no other ions)?" No.

For pure water, the concentration of H+ = that of OH- This isn't necessarily true if the water is not pure. For example in your questions, after adding HCl. But the Value of Kw is the same. The If and However implies different conditions. Not pure water but water containing an acid which will...

If 1000ml contains 1 mole then 100ml contains 0.1 mole and 10ml contains 0.01 moles. So 15.4ml contains 0.0154 moles, not 0.00154 moles. Which is a typo on your part, of course as 0.0154 moles matches your answer of 0.308M. Which is correct answer. Did you get the correct answers for the other...

While using a UV-Vis spectrometer, I found I could see a little bit into the IR and the UV range. The puzzled look on the students faces made me look at the dial I was turning, to realise I could but they couldn't see what I was pointing at.