chem %composition and law of proportions1

chem %composition and law of proportions1

by Darrin Shrontz

​Law of Definite Proportions

​You may want to write down the definitions of these two fundamental concepts of Chemistry.. there will be questions next!

​

Poll

What is the term for the ratio (as a percentage) of each element to the total mass of the compound? 

• definite proportion

• percent by mass

• percent by element

• percent proportion

​This table depicts how % by mass is the same for each element in a compound (of sucrose).

​It is not unusual to be asked questions that ask you to determine the mass of the element, given the % by mass and the total mass of the compound.

Poll

The Law of Definite proportions is...

• compound is always composed of the same proportions and percentage of mass

• compound is always composed of the same elements in the same proportions by mass

• elements are always composed of the same elements in the same proportions by mass

• compounds are not composed of elements, but rather elemental proportionalities

Multiple Choice

What is the term for the ratio (as a percentage) of each element to the total mass of the compound? 

• definite proportion

• percent by mass

• percent by element

• percent proportion

Multiple Choice

The Law of Definite proportions is...

• compound is always composed of the same proportions and percentage of mass

• compound is always composed of the same elements in the same proportions by mass

• elements are always composed of the same elements in the same proportions by mass

• compounds are not composed of elements, but rather elemental proportionalities

Multiple Choice

In a 400 g sample of CsCl, there are 316 grams of Cs. What is the % of Cs in CsCl?

• 41%

• 45%

• 78%

• 89%