Chapter 09, Problem 9.17 Your answer is partially correct. Try again. A 1.5-kg s

Question

Chapter 09, Problem 9.17 Your answer is partially correct. Try again. A 1.5-kg specimen of a 90 wt% Pb-10 wt% Sn alloy Animated F gure 8 is heated to 250°C; at this temperature it is entirely an a-phase solid solution. The alloy is to be melted to the extent that 50% of the specimen is quid the remainder being th a phase. This may be a compli hed either y he ting the allo or changing c it or while holding the temperature constant. a) To what temperature must the specimen be heated? 292 | °C [The tolerance is +/-296.] (b) How much tin must be added to the 1.5-kg specimen at 250°C to achieve this state? 0.18 kg [The tolerance is +/-10%)

Explanation / Answer

Part b

At 250°C   

& (? + L) region

Composition of ? phase

C?

% Sn = 14 %

% Pb = 86%

Composition of L phase

CL

% Sn = 34%

% Pb = 66%

Let the new composition of the alloy = C0

In which (? + L) region
W? = 0.50 = WL

W? = (CL - C0) /(CL - C?)

0.50 = (34 - C0) /(34 - 14)

C0 = 24

% Sn in New composition = 24%

Mass of Sn in 1.5 kg sample = 0.10 x 1.5 kg = 0.15 kg

Mass of Sn added = m kg

(original mass of Sn + mass of Sn added)*100/ ( mass of sample + mass of Sn added) = % Sn in New composition

(0.15 + m)*100/(1.5 + m) = 24

(0.15 + m)*100 = 24*(1.5 + m)

(0.15 + m)*100 = 24*1.5 + 24*m

15 - 24*1.5 = 24m - 100m

m = 0.276 kg

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

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