Swaastikaa

The following system is at equilibrium,at 699K in a 5L container. H2(g)+I2(g)--->2HI(g) Kc = 54.9 Initially,the system had 2.50 moles of HI.What is the moles of H2 at equilibrium? Can Dr.Bob check if my steps are correct? My solution: Initially,the concen...

13 years ago

The reaction: H2PO4- + HAsO42 ---> HPO4- + H2AsO4- Which one of the sets above lists both of the base species involved in the equilibrium? I'm confused and couldn't identify the conjugate acids and bases properly. Could Dr.Bob explain abt this problem ? T...

13 years ago

For the reaction: H2PO4- + HAsO42- ---> HPO42- + H2AsO4- Which pair exists as base in the equilibrium? H2PO4- & H2AsO4- are proton donors,therefore they are conjugate acids. HPO42- & HAsO42- are proton acceptors,therefore they are the base pairs asked in...

13 years ago

If the base sequence along a segment of DNA were TCGTA,what would be the antisense oligonucleotide synthesised from this sequence?

13 years ago

Which one of the following cobalt complexes should be the most stable? a. [Co(NH3)6]2+ b. [CO(NH3)6]3+ c. [Co(en)3]3+ d. [CoF6]3– I think the answer is c, but not really sure. Can Dr.Bob explain ? Thanks

13 years ago

I have a question here: What is the definition of bubble-point line? a) The line that shows when the liquid begins to boil/evaporate b) The vapor-mixture liquid region c) Saturated liquid equilibrium line d) None of the above My textbook says it is satura...

10 years ago

Can someone help me to clarify this question? I'm not sure whether the answer is a), d) or e). What is the definition of the bubble-point line? Select one: a. The line that shows when the liquid begins to boil/evaporate b. The vapour-liquid mixture region...

10 years ago

So,the answers are HAsO42- & HPO4- rite? Because from what I found,HAs04 2- is weakly basic and HPO4 2- is a conjugate base. So the bases are these two species above. M I rite?

13 years ago

But why I can't ignore the 2x? Could Dr.Bob please explain?

13 years ago

The answer should be c). The sum of angles for a triangle is 180 degrees. Since this is an isosceles triangle, it must have two equivalent angles. Therefore 180-26 = 154 degrees. When we divide 154 by 2, we get 77 degrees. So the possible degree measure i...

12 years ago

Hi Ruth,this is easy! Imagine a right angle triangle. In this case, the length of the hypothenuse is 12'.Given the angle of elevation 68 degrees. Since it is a right angle triangle,one of the remaining two angles is 90 degrees. So the third angle is 180-9...

12 years ago

The answer is the same anyway :)

12 years ago

Easy! Using Q = mc(delta) where delta = difference between final and initial temperature Given m = 47 kg Q = 3.40 X 10^2 kJ Since heat is being absorbed into the system, this is an endothermic reaction. c for water is 4.2 kJ/kg.C Substituting Q,m,c & init...

12 years ago

Hi Dee, this is ez! H3O+ is an hydronium ion, a Lewis acid and OH-, hydroxide ion is a Lewis base. Reaction between hydronium and hydroxide yields water molecules H3O+ + OH- ----> 2H2O This is called a neutralization reaction.

12 years ago

Hi Roger, For this problem, you have to cuberoot each of the element (64, x^5 & y^7) separately. For 64 , cuberoot of 64 is 4. x^5 , cuberoot is x^(5/3) y^7, the cuberoot is y^(7/3) Therefore the simplified cube radical form is 4x^(5/3)y^(7/3) Hope this h...

12 years ago

Hi Mary, Q30 : Yes you are correct. Vertex is the highest point of a graph. Moreover,the f(x) cannot be zero because if f(x) = 0, then 2|x| = -4 |x| = -2 ,which is undefined since |x|is always positive. Q21 : The answer is D. Try to substitute a number of...

12 years ago

Hi Brittney, The solution is as follows: Always start with the basic equation: H2 + O2 -----> H2O(l) Balancing the equation above gives: 2H2 + O2------> 2H2O(l) Since 200 molecules of H2 & O2 are involved,just multiply the equation above with 200, 200(2H2...

12 years ago

Thank you Dr.Bob, now I know my mistake.

12 years ago

Hi Shanice, Numbers in total : 1,2,3,4,5,6,7,8 In the first draw : 2 was selected, therefore the probability of drawing a 2 is 1/8. (since there is only one 2 in the list) In the second draw, 3 was selected. The probability is again 1/8. Therefore the ove...

12 years ago

Hi Helen, this is easy! Solving the literal equation for 'a' means expressing the equation in terms of a. Let us see the solutions step by step: a) Multiplying the denominator a-b with y gives : y(a-b) = xab b)Expanding the parentheses y(a-b) gives ya-yb...

12 years ago

The formula is Q = mc(theta), where theta is difference in temperature (final- initial) m = 43g, Cp = 0.90 J/g & theta = 25 degree C Substitute all the values into the equation above: Q = (43)(0.90)(25) = 967.5 J

12 years ago

I disagree that the answer is c < 4. The correct answer is c > 4. Lets see the steps again: x^2 + 4x + c = 0, b^2 - 4ac < 0 4^2 - 4(1)(c) < 0 16 - 4c < 0 16 < 4c 4c > 16 Therefore c > 4

12 years ago

Multiple of 2 = 2,4,6,8,10,12,14,16,18,20,22,24,26,28,30, 32,34,36,38,40,42,44,46,48,50 etc Multiple of 7 = 7,14,21,28,35,42,49,56,63,70 etc So x = 14,28,42,56,70,84,etc You should know the needed x values because you did not mention the range of x

12 years ago

The answer is S. A right angle triangle follows Theorem Phytagoras rule. The sum of squares of 2 sides = length of the 3rd side For S, 25^2 + 20^2 = 1025

12 years ago

Use distance formula: sqrt[(x1-x2)^2 + (y1-y2)^2] x1,y1 = (-2,2) x2,y2 = (4,-6) Substitute all values inside. The final answer is an even integer. Work it out! :)

12 years ago

Assume ideal gas law PV = nRT Since the question mentions constant mass and temperature, P1V1 = P2V2 (1.75)(10.7) = P2(20.0L) P2 = ?

12 years ago

Use M1V1 = M2V2 12 mols/ L X 1 L/1000 mL X V1 = 0.2 mols/L X 1 L/1000 mL X 500 mL Figure out V1 (in mL) .

12 years ago

Square of the 3rd side is the hypothenuse. If we square root 1025, we'll get 5sqrt(41). 5sqrt(41) - 20^2 = 625 = 25^2

12 years ago

Can someone please help to clarify this question? It is very urgent as the due is tomorrow. Thank you.

10 years ago