The Math of Chemistry The Mole And Chemistry Math

What are the big mistakes from naming compounds? Transition metals have to have roman numerals for the CHARGE of the metal. The ONLY compounds that get prefixes are covalent. Only –ide acids begin with hydro.

How are compounds balanced? By adding coefficients in front of the compound to make the same numbers of each element on both sides.

Try these… Silver (I) nitrate and calcium chloride aqueous solutions combined produce a precipitate of silver (I) chloride and leave an aqueous solution of calcium nitrate. Lead (II) nitrate and sodium iodide react to make lead (II) iodide and sodium nitrate

How do I predict products? Use the IONS, change the partners, and swap n drop.

How do I predict the state of matter of the products? Then, use the chart to predict the state of matter of the products. All Br I N Cl H O F are gases, except Br is a (l) and I is a (s) All other elements are (s) except Hg is (l) H 2 O is a liquid and CO 2 is a gas a product As a product, H 2 CO 3 breaks apart into H 2 O and CO 2

Try these: Silver (I) nitrate reacts with copper to make Hydrogen reacts with nitrogen to yield Calcium carbonate reacts with hydrochloric acid to produce

How do we use a ruler/graduated cylinder/etc? You measure to be as exact as possible.

What does that mean? Use the scale listed, and add ONE digit of uncertainty.

For example: What is the measurement? 55.0 cm 56.0 cm 55.33cm Estimated #

13.2 m What is the correct measurement? m 13.1 m

Why do we do this? Because we try to be as exact as possible in science.

What do we use to tell us how precise we were in our measurement? Significant Figures

What is a significant figure? A way of rounding numbers so we are not more precise than our measurements.

In general, how do I round? A 4 and under, stays the same A 5 and up, rounds up. Only look at the neighbor to the place rounding!

What do I do with the rest of the numbers? If it is to the right of a decimal, drop all remaining numbers If it is to the left of a decimal, fill in zeros.

What is the first rule I use for significant figures? All non zero numbers are significant

What about zeros and sigfigs? Zeros are strange, look at each one to figure them out.

What is the first zero rule? Sandwiched zeros are significant

What is the second sig fig zero rule? All zeros at the right of the number are significant, only if a decimal is present

What is the third zero rule? Zeros at the beginning of a number never count

Huh? Wait a minute… Zeros at the end of a number are only significant if there is a decimal present. Zeros at the beginning never count

Try it!

What about scientific notation and sig figs? The number before the x10 n will tell you how many sig figs you have. 6.02x x x x10 97

Round the following numbers to contain 3 sigfigs

Why do I need to figure out the number of sig figs? We have to use the correct number of sig figs in math problems.

What does that mean? 2 more rules!

How do I figure out the number of sig figs in an addition or subtraction problem? You use the least number of DECIMAL places of your input numbers. If a whole number, drop a decimal point at end. (ex. 250., 328., )

DO YOUR MATH FIRST, THEN ROUND! = = = =

What about division and multiplication? You use the least number of sig figs used in the calculation.

3.2 x 5.10= ÷ 13.57= x 9=

Anything weird about rounding? Sometimes you have to put your answer in scientific notation in order to have the correct number of sigfigs in your answer.

What is dimensional analysis? A way of doing math using conversion factors.

What are the conversion factors? They are on a handout

1 hour = 60 minute 7 days = 1 week 1 mL= 1 cm3 24 hours= 1 day 100 cm=1 meter gallons= 1 cubic meter 1 mile= 5,280 feet 20 drops = 1 mL 1 g = ounce 365 days = 1 year 1 L = 1000 mL 2.2 pounds= 1 kg mile = 1.00 km gallon = 1 L 1 inch=2.54 cm 10mm=1 cm 60 second=1 minute 2000 pounds=1 ton 1 kg= 1000 g 12 inches=1 foot 3 feet= 1 yard 1000 (base unit)=1kilo(base unit)

How do I do dim analysis? You use the conversion factors to cancel out units.

How do I use sig figs with dim analysis? Conversions don’t count in sig figs, so end with the same amount of sig figs that you start with. (they are exact)

Examples: Convert 4800kg into pounds. Convert 22.5 hours into seconds. Convert 6.9gallons into drops.

The Mole!!! ETVmg&index=9&list=PLA E https:// ETVmg&index=9&list=PLA E

How are things counted? Pair, dozen, gross, ream

How do chemists count things? In moles.

Mole Origin: German Mol, short for Molekül (molecule)

What is a mole? 6.02x10 23 of something

It is estimated there is about 1 mole of grains of sand on earth. 1 mole of marshmallows would be enough marshmallows to make a 19 km (12 mi) thick layer of marshmallows covering the entire face of the Earth. 1 mole of popcorn kernels could be spread uniformly over the USA if the thickness of the layer was about 14 km (9 mi). 1 mole of donut holes would cover the earth and be 8 km (5 mi) deep. 1 mole of blood cells would be more than the total number of blood cells found in every human on earth. 1 mole of pennies could be distributed to all the currently-living people of the world so that they could spend a million dollars per hour every hour (day and night) for the rest of their lives.

Why do chemists use the mole to count? Atoms and molecules are ridiculously small.

What is the name of the number 6.02x10 23 ? Avogadro’s Number

Why are moles bad at counting? Because they only know one number.

How do we use Avogadro’s number? To convert from moles to particles

How do I do that? Use the conversion that 1 mole = 6.02x10 23 particles (atoms, molecules, formula units).

3.4 moles of NaCl= ? formula units

8.765x10 29 molecules = ? moles

6.5 moles of Aluminum= ? Atoms

5.7x10 19 atoms Cl 2 = ? moles

How do you find the mass of one mole? You use the molar mass.

What is molar mass? It is the mass of one mole of something.

How do you find molar mass? Use the mass on the periodic table. Add each element’s mass.

I thought the mass on the PT was in amu. The mass of one atom (p + + n o ) is in amu. The mass in grams is the mass of one mole of the same element.

How do I write molar mass? 1 mole = ______________g

What unit is used to find molar mass? Grams (in 1 mole)

Examples: Zinc (II) Chloride Bromine Aluminum Diphosphorus pentoxide Gallium acetate

How do I use dim analysis to solve chemistry problems? 1 mole = _____________g (molar mass) Or 1 mole = 6.02x10 23 atoms/molecules/formula units

How many moles are in 56.98g of AgI?

How many grams are in 75.1 moles of Copper (II) Sulfate?

How many formula units are in 45.9g of sodium carbonate?

If you have 5.7x10 26 formula units of NiO, how many grams is this?

What is percent composition? It is finding the percentage by mass of the individual elements in a compound.

How do I find percent composition? Total Element Mass x100 Total Compound Mass This is done for EACH element asked for in the problem!

Example Find the percent composition of each element in Lead (II) Nitrate.