Ma 3- Law of Definite Proportions

Which statement is the Law of Definite Proportions?

• Matter can not be created nor destroyed, just change form
•  A given chemical compound always contains its component elements in fixed ratio (by mass)
• when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.
• “Success = 1 part work + 1 part play + 1 part keep your mouth shut”

Tags

NGSS.MS-PS1-1

A 85g sample of a compound contains 43g of carbon. What is the percent by mass of carbon in the compound?

• 198%

• 43%

• 59%

• 51%

What is the % by mass of oxygen O in CO₂ if a 52g sample of carbondioxide (the compound) contains 15g of oxygen (the element)?

• 19%

• 49%

• 29%

• 39%

Tags

NGSS.MS-PS1-1

In an experiment, 75g of CuO (the compound) was decomposed and 22.5g of Cu (the element) was left. The oxygen had escaped into the air.. What is the % Cu in the compound?

• 35%

• 36%

• impossible to tell

• 30%

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

NGSS.MS-PS1-2

In an experiment, 55g of CuO was decomposed   and  44g of  Cu was left. The oxygen had escaped into the air.. What is the % O in the compound?

• 20%
• impossible tot ell
• 16%
• 80%

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

If 43g of element X, combines with 4.2g of element Y and 5.6g of element Z to form XYZ, what is the percent by mass of element X?

• 70%

• 81%

• 43%

• 65%

Tags

NGSS.MS-PS1-5

If 43g of element X, combines with 4.2g of element Y and 5.6g of element Z to form XYZ, what is the percent by mass of element Y?

• 4%

• 7%

• 8%

• 12%

Tags

NGSS.MS-PS1-5

If 43g of element X, combines with 4.2g of element Y and 5.6g of element Z to form XYZ, what is the percent by mass of element Z?

• 6%

• 7%

• 11%

• 15%

Tags

NGSS.MS-PS1-1

What is the formula for percent by mass?

• mass of element divided by mass of compound multiplied by 100.

• mass of compound divided by mass of element multiplied by 100

• mass of element divided by 100 multiplied by mass of compound

• mass of compound divided by 100 multiplied by mass of element.

Tags

NGSS.MS-PS1-5

A 105g sample of a compound contains 54g of element Q, what is the percent by mass of element Q?

• 52%

• 51%

• 50%

• 53%

Tags

NGSS.MS-PS1-1