CHE 2A Lecture Notes - Lecture 11: Isopropyl Alcohol, Molar Mass, Chemical Formula
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Zeros appearing between nonzero digits are significant. Zeros appearing in front of nonzero digits are not significant. Zeros at the end of a number and to the right of a decimal are significant. Addition/subtraction: as precise as the least precise measurement to the right of the decimal ex) 12. 18701 (5 numbers to the right of decimal) + 0. 0673 (4 numbers to the right of decimal) least amount. Multiplication/division: as precise as the least precise measurement ex) 12. 257 (5 sig figs) x 1. 162 (4 sig figs) least amount. Tip: don"t apply significant figures until the end of a problem. 16: the total molar mass of the compound, h2o is 18 g/mol, to calculate the percent we divide the individual mass by the total mass, then multiply by. 100, h: 2/18 = 0. 111 x 100 = 11. 1% hydrogen, o: 16/18 = 0. 889 x 100 = 88. 9% oxygen.
