FOLLOW US ON TWITTER
SHARE THIS PAGE ON FACEBOOK, TWITTER, WHATSAPP ... USING THE BUTTONS ON THE LEFT


YOUR PARTICIPATION FOR THE GROWTH OF PHYSICS REFERENCE BLOG

Friday, April 10, 2020

A nuclear reaction occurs when a uranium-235 nucleus absorbs a neutron. The reaction may be represented by the equation


Question 18
(a) A nuclear reaction occurs when a uranium-235 nucleus absorbs a neutron. The reaction may be represented by the equation:

23592U   +          WX n     - - - >  9337Rb +         141ZCs +          YWX n

State the number represented by the letter
W .............................................................
X ..............................................................
Y ..............................................................
Z ...............................................................
[3]


(b) The sum of the masses on the left-hand side of the equation in (a) is not the same as
the sum of the masses on the right-hand side.
Explain why mass seems not to be conserved. [2]





Reference: Past Exam Paper – June 2012 Paper 22 Q7





Solution:
(a)
W = 1 and X = 0                    
{WX n is a neutron. So, W = 1 and X = 0}
Y = 2                                      
Z = 55                                    
{On both sides, the total proton number and nucleon number should be the same.
Proton numbers:
92 + 0 = 37 + Z + (y×0)
Giving Z = 55

Nucleon numbers:
235 + 1 = 93 + 141 + (y×1)
236 = 234 + y
y = 236 – 234 = 2}


(b)
Mass–energy is conserved.
{Some of the mass is converted to energy, such that energy E = Δmc2 where Δm is the difference in mass. So, the mass is actually conserved, but it is now on the form of energy.}

Energy is released as gamma or photons or kinetic energy of products or EM radiation.

No comments:

Post a Comment

If it's a past exam question, do not include links to the paper. Only the reference.
Comments will only be published after moderation

Currently Viewing: Physics Reference | A nuclear reaction occurs when a uranium-235 nucleus absorbs a neutron. The reaction may be represented by the equation