holy crap this is like a gauntlet
i need help with this question
and is this reaction exothermic or endothermic because i thought it was exothermic
Thanks!
Well, why do you think it's exothermic?
Hey guys I need help with redox reaction questions, I still find it quite hard.
Sure, what do you find so hard about them? Where do your problems lie?
i need help urgently. pls
how do you work out solution 5 has the highest pH
Well, pH is inversely proportional to the concentration of hydronium ions in solution - so the solution with the highest pH will have the lowest concentration of hydronium ions. This is a picture, not a number, so you need to think about this conceptually. If you look at the equation:
How do you make this number, C, smaller? Either by making the numerator smaller, or the denominator bigger (if this confuses you, think about what happens to the decimal form of 2/3 if you make 3 a bigger number or 2 a smaller number). So, which picture has the smallest n but the biggest V?
LOL I love how you actually did it - soz I don't exactly check every question that's ever been asked. So we don't need to know anything about Ka? Also would we need to know about the concentration fraction? (I'm just seeing all these terms in past VCAA exams and want to know if they're still assessable)
I've attached a picture of a question from the 2013 VCAA exam
Thank you.
I mean, theoretically, you could still be given an equation like this in your exam:
Then asked to calculate the equilibrium constant, asked to find the concentration of hydronium ions, etc., but you wouldn't be expected to recall any of this by yourself - you'd have to be guided through the material, just like you would be on any other equilibrium question.
Yeah, in this case, they're using %ionisation as an acid-base term, you don't need to know how to calculate it (sidenote: this was the exam I did and I don't remember that question or how to calculate it, oops). If you see a term in a past exam that you don't recognise, and it's at all related to something you know is removed from the study design, tbh you're better off just assuming that you don't need to know how to calculate it - there are still PLENTY of exams relating to this study design that will tell you if something's worth remembering or not. Typically, VCAA will have covered every type of concept they might ask about in a span of two years. A new year's exam might seem different in the way they've "dressed up" the questions, but the core concepts (including equations you should need) should be the same.
This may be a naïve question but do you include the amount of sig figs in a temperature figure given on a question?
See ArtyDreams. +1. All sig figs are real sig figs.
What would be the easiest way to write the half Equation in a fuel cell which involves ethanol and produces carbon dioxide in alkaline cell?
I tried this question for 15 minutes but could not get and I have the answer but the it was hard! The way I go about balancing is C——>H——>O and I balanced the O with water and the H with OH- because it’s alkaline conditions
Yeah, so alkaline cells are difficult in that way because adding in hydroxide ALSO adds in H, not just O. The easiest way to do these types of questions is to balance them out the same way you would for acidic conditions. Then, whichever side has the free protons, add in the same amount of hydroxide on BOTH sides of the equation. Eg, let's say we have:
We have 8 free protons on the left side of the equation, so let's add 8 hydroxides to both sides:
Any free protons and hydroxide ions will combine to make water:
Cancel out the excess water:
And you're done! A balanced electrochemical reaction in alkaline medium. Why don't you try this for your question, now?
For this question
When a reaction is at equilibrium and more reactant is added which of the following changes is the immediate result?
A the forward reaction rate remains the same
B the forward reaction and the reverse reaction remain the same
C the reverse reaction rate increases
D the forward reaction rate increases
Would it be D
Why do you think D would be correct?