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An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99 amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average atomic mass of this element. Click here to see a video of the solution.
There are four steps involved in solving these problems: Make sure you are working with a properly balanced chemical equation. Convert grams of the substance given in the problem to moles. Construct two ratios - one from the problem and one from the chemical equation and set them equal.
May 28, 2020 · PROBLEM \(\PageIndex{7}\) Which contains the greatest mass of oxygen: 0.75 mol of ethanol (C 2 H 5 OH), 0.60 mol of formic acid (HCO 2 H), or 1.0 mol of water (H 2 O)? Explain why. Answer . Formic acid. Its formula has twice as many oxygen atoms as the other two compounds (one each).
Jul 30, 2020 · Solution. First, let us work the problem in stepwise fashion. We begin by converting the mass of \(\ce{CH4}\) to moles of \(\ce{CH4}\), using the molar mass of \(\ce{CH4}\) (16.05 g/mol) as the conversion factor: \(\mathrm{100.0\: g\: CH_4\times\dfrac{1\: mol\: CH_4}{16.05\: g\: CH_4}=6.231\: mol\: CH_4}\)
Sep 19, 2017 · Solution: Boron is made up of 20% B-10 and 80% B-11. Atomic mass is the sum of the masses of the protons and neutrons in an atom. These example problems show the how to calculate the atomic mass of an element.
This is a comprehensive, end-of-chapter set of practice problems on stoichiometry that covers balancing chemical equations, mole-ratio calculations, limiting reactants, and percent yield concepts. The links to the corresponding topics are given below. The Mole and Molar Mass. Molar Calculations.
Example #7: How many molecules (not moles) of NH 3 are produced from 1.75 x 10¯ 4 g of H 2? Express your answer numerically as the number of molecules. Solution: 1) Write the balanced chemical equation for the reaction: 3H 2 + N 2---> 2NH 3. 2) Determine moles of H 2 present:
