[katertatters]

1) "How many atoms are in 1.40 mol of carbon-12?"


2) Lead compounds are often highly colored and are toxic to mold, mildew, and bacteria, properties that in the past were useful for paints used before 1960. Today we know lead is very hazardous and it is not used in paint, however, old paint is still a problem. If a certain lead-based paint contains 15.0% PbCr2O7 and 82.5% of the paint evaporates as it dries, what mass of lead (in grams) will be in a paint chip that weighs 0.73 g?


Completely not sure how to go about this, i am very rusty!

[Hunter2]

!. Do you know Avogadro constant?

2. Simple mathematics- The chip paint is dry, the weight after paiting was about 85% higher. The mass contains 15% lead bi chromate. Here calculate the moles of it and then backward the mass of lead.