Solving Stiochemistry

Rebecca Ledezma (Period 5)

NAME OF REACTION

Sodium Sulfate Na2SO4

& Strontium Nitrate Sr(NO3)2

TYPE OF REACTION

DOUBLE REPLACEMENT: When the reactants are a compound of a metal (Na) and polyatomic (SO4) plus another metal (Sr) and polyatomic (NO3). They switch to form the products. The metals switch places so they are now paired with a different Polyatomic. The metal must come first and then the polyatomic. The subscripts on the products side may be different than those on the products side, because you cross/switch up the compounds.

BALANCED EQUATION

1 Na2 SO4 (aq) + 1 Sr(NO3)2 (aq) -----> 2 NaNO3 (aq) + 1 SrSO4 (s)

To be a balanced equation, it must have the same amount of each element on the reactant side as the product side. When writing an equation for double replacement, you must also have the states of matter for each compound.

IUPAC NAMING

Sodium Sulfate + Strontium Nitrate ---> Sodium Nitrate + Strontium Sulfate

MOLAR MASS

To find the Molar mass for each element, look at the periodic table. You multiply the mass by any subscript or coefficient meant for the element.

Na2SO4

Na: 22.99 (2) + S: 32.066 (1) + O: 15.99(4) = 142.042 g

Sr(NO3)2

Sr: 87.62 (1) + N: 14.007 (2) + O: 15.99 (6) = 211.628 g

NaNO3

Na: 22.99 (1) + N: 14.007 (1) + O: 15.99(3) = 84.967 g

SrSO4

Sr: 87.62 (1) + S: 32.006 (1) + O: 15.99(4) = 183.662 g

How to Calculate Molar Mass

MOLE TO MOLE CONVERSIONS

To do mole to mole conversions, you must start with a given amount of "Mole A". You then multiply it by "Mole B". You know what to mulitply "Mole B" by because its coefficients. You find the coeffiecents from the balanced equation. Lastly, you divide the products of "Mole A" and "Mole B" by the coeffiecent of "Mole A". Your units should cross out to leave you with only one ending unit. MULTIPLY ON TOP, DIVIDE BY BOTTOM.


8.25 mole Na2SO4 • 1 mole Sr(NO3)2

________________________________________ = 8.25 mole Sr(NO3)2

1 mole Na2SO4



8.25 mole NaNO3 • 1 SrSO4

______________________________ = 4.125 mole SrSO4

2 mole NaNO3

MASS TO MASS CONVERSION

12.1 g Na2SO4 • 1 mole • 1 mole Sr(NO3)2 • 211.628 Sr(NO3)2

______________________________________

142.042 g Na2SO4


= 18.03 g Sr(NO3)2


*look at chart for guidance*

Mole-to-mole and Mass-to-mass Conversions

LIMITING & EXCESS REACTANT

Limiting: element that runs out

Excess: element left over

In the Smore's lab, the limiting reactant was the chocolate. The excess reactant was the crackers and marshmallows.


12.3 g Na2SO4 • 1 • 2 • 107.78 NaNO3

_______________________________________ = 18.66 g NaNO3

142.042 Na2SO4 •1 • 1 NaNO3


*12.3 g of Na2SO4 is your excess reactant*

THEORETICAL YIELD

THEORETICAL YIELD: calculated amount of the reaction you can make, assuming all The measurements are correct.


12.3 g Sr(NO3)2 • 1 • 2• 107.78 NaNO3

________________________________________ = 12. 53 g NaNO3

211.628 Sr(NO3)2 •1 • 1 NaNO3


* 12.3 g of Sr(NO3)2 is your limiting reactant*

*12.53 g NaNO3 is your theoretical*

PERCENT YIELD

Percent Yield Formula: Actual Yield/ Theoretical Yield • 100


Actual Yield: 13. 42 g NaNO3


13.42/12.53 • 100 = 107.1%

BACKGROUND OF REACTION

SODIUM SULFATE: soluable in water, in passive solar heating

STRONTIUM NITRATE: Used in the production of color tv tubes, sources are Mexico, Iran, Turkey, and Spain