For the following formula, classify the reaction as formation, decomposition, combustion, or none of these.

2HgO_(s)  →    2Hg_(l)  +  O_2(g)

Decomposition

A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:

For the following formula, classify the reaction as formation, decomposition, combustion, or none of these.

8 Fe + S₈ ---> 8 FeS

Formation

A reaction that starts with 2 or more elements and produces one compound

For the following formula, classify the reaction as formation, decomposition, combustion, or none of these.

2FeCl (s) + Br (g) ------> BrCl₄ (ag)  + 2Fe

For the following formula, classify the reaction as formation, decomposition, combustion, or none of these.

C₁₀H₈ + 12 O₂ ---> 10 CO₂ + 4 H₂O

Combustion:

 A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

Write the chemical equation for the formation of

CaCO₃

A. Ca + C + O₂  -----> CaCO₃

this is not balanced yet

B. 2Ca + 2C + 3O₂  -----> 2CaCO₃

now it is balanced

Write the chemical equation for the decomposition of:

PbSO₄

A. PbSO₄  -----> Pb + S + O₂

not balanced yet

B. 2PbSO₄ -----> 2Pb + 2S + 4O₂

now it is balnced and broken down into its constituents

Write the chemical equation for the complete combustion of

CH_4(g) + 2O_2(g)

CH_4(g) + 2O_2(g) ----> 2H₂O_(g) + CO_2(g)

What is the mass of a calcium atom in kg?

40.1amu  x  1.66 x 10^-24g   x    1kg             

    1             1 amu             1,000g     =       

What is the mass of an C₄H₆O₂ molecule in amu?

 C= 12 x 4 = 48

H=1.01 x 6 = 6.06

O=16 x 2= 32

48+6.06+32 =86.06

86.06 amu is the answer

How many moles are in  24.2g of C₄H₆O₂

We already know there is 86.06 amu from the previous card.

This means 1 mole is equal to 86.06grams. Now we can use this in a conversion:

24.2g  x   1mole  

   1         86.06g    =   0.2812 moles

If a chemist has 10.5 moles of C₄H₆O_2,what is the mass of the sample?

Again, we know there is 86.06 amu

This means 1 mole = 86.06. Now we can convert from moles to grams

10.5moles x  86.06g 

     1            1 mole   = 903.63g is the answer

First we need to figure out the decompression reaction:

Ca₂CO₃   -----> Ca + C + O₂

This is not balanced, so lets balance the equation:

2Ca₂CO₃   -----> 2Ca + 2C + 3O₂ (now its Balanced)

Thus 2 moles of Ca₂CO₃ = 3 moles of O₂

So now we can figure it out:

 .025 moles of Ca₂CO₃   x   3 moles O₂ 

               ₁                              2 moles of Ca₂CO₃ 

= 0.375 moles of O₂

Which sample has more atoms in it:

12 grams of Copper (Cu) or 15 grams of Potassim (K)

To count atoms, we need to know how many moles. Thus, we need to take these masses and convert them to moles

12gCu  x 1 mole Cu 

   1         63.5gCu       = 0.189 moles of Cu

15gK   x  1 mole K       

   1         39.1gK        =  0.383 moles of K

Thus 15g of Potassum has more atoms than 12 grams of Copper.

Since we have one mole, the mass of the sample in grams is also the mass of the molecule in amu. Thus, we know that this molecule mass is 48.3 am. Since it has 2 molecules of carbon, the carbon atoms take up 24 amu of that mass. Thus, 24.3 amu are left for "X". If you look at periodic chart. the only atom with a mass 24.3 is Magnesium (Mg).

So "X" is Magnesium