Law of Multiple Proportions
What is the law of multiple proportions?
The law of multiple proportions states that if elements form more than one compound, those comppounds will have compositions that are small, whole-number multiples of each other.
Name 4 methods of separating mixtures.
Answers could be: crystalization, chromotography, distilation, filtration, and evaporation
What is the law of definite proportions?
The law of definite proportions states that a chemical compound always contains the same elements in the same proportions by mass, regardless of its source.
Carbon reacts with oxygen to form two different compounds. Compound 1 contains 4.82 g of carbon for every 6.44 g of oxygen. Compound 2 contains 20.13 g of carbon for every 53.7 g of oxygen. What is the ratio of carbon to oxygen for compound 1 to compound 2?
2:1
What is the best method to separate dissolved copper sulfate from its solution to obtain crystals?
Crystallization
What is the equation to find percent by mass?
Percent by mass = Element mass/compound mass.
Two unknown compounds are tested. Compound 1 contains 8 g of hydrogen and 128 g of oxygen. Compound 2 contains 25 g of hydrogen and 480 g of oxygen. Are the two compounds the same? Show your work and explain.
The compounds are not the same because their ratios by mass are different. The mass ratio for compound 1 is 1/16. The mass ratio for compound 2 is 5/96.
What is the best method to separate salt dissolved in water?
Evaporation
A 25.3g sample of an unknown compound contains 0.8g of oxygen. What is the percent by mass of oxygen in the compound?
About 3.16%
Explain how the law of definite proportions and the law of multiple proportions lead to and support the idea that matter is made of atoms?
The Law of Definite Proportions involves fixed ratios that imply that each compound has a unique, unchanging atomic structure, not a variable mixture. The Law of Multiple Proportions involves whole-number ratios that imply that atoms combine in discrete, countable units rather than in arbitrary amounts.
What is the best method to separate two pharmaceutical products dissolved in water without breaking them down?
Chromotography
Magnesium combines with oxygen to form magnesium oxide. If 10.57 g of magnesium reacts completely with 6.96 g of oxygen, what is the percent by mass of oxygen in magnesium oxide?
About 39.7%
Why do separation techniques work to separate mixtures in general? How does a mixture differ from a chemical reaction? Explain.
They work because mixtures still have the separate components, they are not chemically combined. A chemical reaction creates a totally new substance that cannot be separated like a mixture can.
When mercury oxide is heated, it decomposes into mercury and oxygen. If 28.4 g of mercury oxide decomposes, producing 2.0 g of oxygen, what is the percent by mass of mercury in mercury oxide?
About 93%