A sample containing beryllium (atomic mass 9 u), aluminum (27 u), and an unknown

Question

A sample containing beryllium (atomic mass 9 u), aluminum (27 u), and an unknown element is placed in a mass spectrometer. The ions all have the same charge and are accelerated through the same potential difference before entering the magnetic field. The beryllium and aluminum lines are separated by 2.300 cm on the photographic plate, and the unknown element makes a line between them that is 0.634 cm from the beryllium line. (a) What is the mass of the unknown element? _______ u (b) Identify the element, using its chemical symbol. (Note that there may be more than one correct answer.)

Explanation / Answer

The deflection in atoms is determined by following deflection is inversely proportional to (m/z), as ahave same charge assume it to be +1 charge and mass of beryllium =+1, 9u , m/1 = 9 and on aluminium = +1, 27u, m/1 = 27 thus charge and mass ratio suggests that aluminum will be least deflected and Be more so if Al isdeflected by x then Be is deflected by x+1.8 hence, deflection of Be/Al = (x+1.8)/x = 27/9 ( as inversely proportional) x+1.8 = 3x = > x = 0.9 Now lets say charge by mass for new element is y then, deflection of M/Al= (x+1.8-0.921)/0.9 = 27/y y = 27/(0.9+1.8-0.921) =15.177 u thus massof element is nearly 15u b) So as it can be oxygen or Nitrogen depending on theor atomic mass

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.