The amount of copper is a sample was determined using atomic absorption spectrom

Question

The amount of copper is a sample was determined using atomic absorption spectrometry. A series of measurements using standard Cu solution yielded the calibration curve shown below. The slope and y-intercept of the least-squares fitted line are. slope = 0.1156 plusminus 0.0087 y-int = -0.0224 plusminus 0.0236 An unknown copper sample gave a signal value of signal = 0.3486 plusminus 0.0128 abs units. (a) What is the final concentration of copper in the unknown sample? (b) What is the uncertainty in the value of the unknown copper concentration?

Explanation / Answer

2. y = mx + c

y = 0.1156 (+/- 0.0087)x - 0.0224 (+/- 0.0236)

with,

y = 0.3486 (+/- 0.0128)

we get,

(a) final concentration of copper in the unknown sample = (0.3486 + 0.0224)/0.1156 = 3.2093 ppm

(b) maxima Cu concentration = (0.3614 + 0.046)/0.1243 = 3.2775 ppm

minima Cu concentration = (0.3358 + 0.0012)/0.1069 = 3.1525 ppm

uncertainty = (3.2775 + 3.1525)/2 = +/- 0.0057

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