CHEM 1070 Lecture Notes - Lecture 1: Signify, Reagent, Empirical Formula

16 views13 pages

magentabuffalo107

14 Jun 2021

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Chemical formula gives the whole-number ratio of moles of elements in the compound. Example: 200. mg of bitter alkaloid and psychoactive stimulant, caffeine (c8h10n4o2), were ingested at 6 am. Answer: 8 c : 10 h : 4 n : 2 o molar ratio of elements 4 moles of n in 1 mole of caffeine. Chemical formula gives the whole number ratio of moles of elements in the compound. Conversion: # moles --> mass: molar mass of element (periodic table) To calculate %%%, divide the part (mass of element) by the whole (mass of compound) Mass % cl = (2 x molar mass of element / molar mass of compound) x 100% Mass percent composition or mass percent of an element is the element"s percentage pf the total mass of the compound. Empirical formula: simplest whole number ratio of the elements in a compound. Lab analysis often provide masses of each element in compound, not chemical formulas.

Related Questions

1) How many atoms are there in 51.3 g of barium chloride (BaCl2)?
2) How many moles of carbon monoxide (CO) are in 29.3 g of the compound?

3) What is the formula for copper(II) phosphate? Capitalization and punctuation count?

4) How many atoms of phosphorus are in 2.90 mol of copper(II) phosphate?

5) How many moles of N are in 0.191 g of N2O?

6) A sample of C3H8 has 7.68 Ã 1024 H atoms. How many carbon atoms does the sample contain? What is the total mass of the sample?

7) Calculate the percent composition by mass of each element in Al(OH)3. Use at least three significant figures.

% Al= ?, % O=? , % H =?

8) What is the empirical formula of a compound composed of 3.25% hydrogen (H), 19.36% carbon (C), and 77.39% oxygen (O) by mass?

HCO (Insert subscripts as needed.)

9) A compound with the empirical formula CH2 has a molar mass of 98 g/mol. What is the molecular formula for this compound?

Determine the simplest whole number mole ratio of C,H and O in the unknown using the 5 of 6 character format such as C2H30, C3H40, C2H3O2, etc. If a coefficent for a given element is 1, omit it from the empirical formula.

State the answer as CxHyOz - ?

Mass of O - 0.8246g Moles of O - 0.05

Moles of H atoms - 0.172 moles Moles of C atoms - 0.050

Moles of H2O - 0.086 moles Moles of CO2 - 0.050

Compare the moles of C, moles of H and moles of O and determine which value is the smallest. Now take the moles of each atom (C, H, and O) and divide each by the smallest value. The whole number that you get for each atom will give you the empirical formula for catechol.

CHEM 1070 Lecture Notes - Lecture 1: Signify, Reagent, Empirical Formula

Document Summary

Get access

Related textbook solutions

Chemistry: Structure and Properties

Basic Chemistry

Principles of Chemistry Molecular Approach

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related Documents

CHEM 1070 Study Guide - Final Guide: Heat Capacity, Chemical Equation, Chemical Formula

CHEM 1070 Chapter Notes - Chapter 5: Unified Atomic Mass Unit, Binary Phase, Roman Numerals

Related Questions