AP Chemistry Question of the Day --60

Welcome back to my blog. Here is question 59 I posted last week.

59.  Which of the following best helps to account for the fact that the F^- ion is smaller than the O^2- ion?                                                     

(a) F^- has a larger nuclear mass than O^2-    

(b) F^- has a larger nuclear charge than O^2-   

(c) F^- is more electronegative than O^2-        

(d) F^- is more polarizable than O^2-.

The correct answer is b.  Both fluoride and oxygen ions have 10 electrons. They are isoelectronic to each other. The size of the ions is determined by the number of protons in the nucleus. Since fluoride has 9 and oxygen has 8 protons. The electrons in fluoride ion experience more attraction from the nucleus and makes the ions smaller.

Statement A and C are both correct but they are not the right explanation.

Here is question 60 of the series:

60. Glycerol has lower vapour pressure than does ethanol at room temperature. Which of glycerol and ethanol has the lower boiling point?

Thank you very much for visiting my blog. I am available to discuss any topics in Chemistry at all levels. Please shoot me an email at vancouverchemistrytutor@gmail.com or give a call at 604-808-6827.

AP Chemistry Question of the Day --54

Welcome back to my blog. Following is Question 53 I posted earlier. The correct answer is E.

53.  A solution appears yellow.  It must be absorbing in the  

    (a) yellow only    (b) red only    (c) green only    (d) blue only   (e) purple only.

I am always surprised when my students are confused with colours. As we know, the sunlight consists of UV, visible and infrared lights. The visible region is white (or colourless) when combined. It is actually a mixture of all the colours of the rainbow: red, orange, yellow, green, blue and purple. If a subject appears to be white, then it absorbs no visible light and reflects all the colours. If a subject appears to be black, then it absorbs all the colours of the visible region. If a subject appears a particular colour, for example yellow as stated in the above question, then it reflects only yellow light and absorbs the rest of the colours. The colour that was absorbed should be complimentary to yellow, which means when combined with yellow, it will be black. What colour is absorbed then:
There are three primary colours: red, yellow and blue, as shown below:

If only yellow light was reflected, then red and blue was absorbed and the combination of red and blue is purple. As a result, purple light was absorbed.

Following is question 54 of the series:














I will post the answer in my next blog.

Thank you very much for reading my post, I am available to discuss any topics in chemistry. Please give me a call at 604-808-6827 or email me at vancouverchemistrytutor@gmail.com. My website is located at www.vancouverchemistrytutor.com.

Regards!

AP Chemistry Question of the Day --51

Welcome back to my blog. The correct answer for Question 50 is A. As you go from left to right in the same period, more effective nuclear charge is experienced. As a result, you will see smaller radius, higher ionization energy, higher electron affinity and higher electronegativity. There is no doubt that atomic mass is increasing because of the increased atomic numbers.
Here is question 51 of the series:
51.  According to the Lowry-Brønsted definitions, which chemical species can function either as an acid and as a base, depending on the conditions?

I will post the answer in my next blog.

Thank you very much for reading my post, I am available to discuss any topics in chemistry. Please give me a call at 604-808-6827 or email me at vancouverchemistrytutor@gmail.com. My website is located at www.vancouverchemistrytutor.com.

Regards!

AP Chemistry question of of the day--50

As I am getting less busy, I will resume my series of chemistry question of the day. Here is my last question I posted last November.

49. What is the solubility of lead (II) bromide at 298K if Ksp of lead (II) bromide is 6.6x10-6?

The solubility equilibrium of lead (II) bromide can be represented as:

and the Ksp can be expressed as 

assume the solubility of lead (II) iodide is xM, then

by solving the equation we can find the solubility of lead (II) iodide to be 1.2x10-2. Pay attention here that I keep 2 significant figures for my answer as the original kip in the question has two sig figs.

Here is question 50 of the series:

50. which of the following properties generally decrease across the periodic table from Na to Cl?

A. atomic radium

B. Atomic mass

C. electronegativity

D. first ionization energy

I will post the answer in my next blog.

Thank you very much for reading my post, I am available to discuss any topics in chemistry. Please give me a call at 604-808-6827 or email me at vancouverchemistrytutor@gmail.com. My website is located at www.vancouverchemistrytutor.com.

Regards!