Hello. I just started a first year chemistry course after switching to the sciences from the arts, and wanted to double-check some equations with you because this is a little new to me. I'm good with the qualitative stuff, but the quantitative parts come a little harder.(adsbygoogle = window.adsbygoogle || []).push({});

Q1: A sheet of metal is 93.3 mm wide and 40.6 mm long. If it weighs 4.877 g and the density of the metal is 1.74 g/cm3, what is the thickness of the sheet (in mm)?

My answer: 4.877g / 1.74g/cm^3 = 2.80cm^3

93.3mm x 40.6mm = 3780mm (3 sig figures)

2.80cm^3 / 3780mm = 0.740mm

93.3mm x 40.6mm x 0.740mm = 2.80cm^3

Thus, the sheet is 0.740mm thick.

Q2: If PV = [gR(T+273.15)]/M, solve for M when P = 334, V = 0.350, g = 0.274, R = 62.37, and T = 39.

My answer:

PV = [gR(T+273.15)] / M

(334)(0.350) = (0.274) (62.37) (312.15) / M

116 = 5330 (3 sig figures) / M

116 / 5330 = M

0.0217 = M

Q3: An ore contains 42.3 % of the mineral ilmenite, FeTiO3, which is a source of the element Ti. How much ore must be processed in order to obtain 41.0 kg of Ti?

Molar masses

Fe = 55.85g

Ti = 2004.4g

O = 16.00g x 3 = 48.00g

total = 308.2g

308.2g / 204.4g = 1.50

41.0kg x 1.50 = 61.5kg

100 / 42.3 = 2.36

61.5 x 2.36 = 145 kg of ore are needed to obtain 41.0kg of thallium.

Thank you all in advance.

M.

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# Homework Help: Basic Chemistry Calculations

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