200 Things You Must Know to Pass High School Chemistry

 

31.  Use the mole map to help you solve conversions

       between moles, grams, numbers of molecules/atoms, and liters of gases at STP.

 

Given the reaction CH4 + 2O2 --> CO2 + 2H2O,
what amount of carbon dioxide is produced by the reaction of 1 mole of CH4?

                                    1 gram             1 liter               1 mole              22 grams

 

36. Coefficients are written in front of the formulas of reactants and products to balance chemical

equations.  They give the ratios of reactants and products in a balanced chemical equation.

           _____Na          +          _____Cl2        --->        _____NaCl

 

41. Physical changes do not form new substances.

They merely change the appearance of the original material.  (The melting of ice) H2O (s)  --->  H2O (l)

 

42. Chemical changes result in the formation of new substances.

            Which process is an example of a chemical change?

the melting of ice                     the electrolysis of water                       the boiling of water

 

43. Reactants are on the left side of the reaction arrow and products are on the right.

 

46. Only coefficients can be changed when balancing chemical equations!

            Given the unbalanced equation: Al + O2 = Al2O3

When this equation is balanced using the smallest whole numbers, what is the coefficient of Al?

1                      2                      3                      4

 

47. Synthesis reactions occur when two or more reactants combine to form a single product.                  

Na (s)  +  Cl2(g)   --->   ____

 

48. Decomposition reactions occur when a single reactant forms two or more products                                                    CaCO3(s)    --->   CaO(s)  +  ____

 

49. Single replacement reactions occur when one element replaces another element in a compound.      

Which equation below represents a reaction classified as a "single replacement" reaction?

2 H2 + O2 --> 2 H2O

Pb(NO3) 2 + K2CrO4 --> 2 KNO3 + PbCrO4

                           HCl + NaOH --> H2O + NaCl

                           Cu + Zn(NO3) 2 --> Zn + Cu(NO3) 2

                           CaCO3 --> CO2 + CaO

 

50. Double replacement reactions occur when two compounds react to form two new compounds.

            Potassium sulfide is mixed with lead acetate. Which of the following products is expected?

                        PbSO4              K2S      K3PO4              PbS                  Pb(C2H3O2)2

 

51. The masses (and energy and charge) of the reactants in a chemical equation is always equal to

the masses (and energy and charge) of the products.  “Law of Conservation of Mass(and Energy).”

 

52. The gram formula mass (molar mass) of a substance is the sum of the atomic masses of all the atoms in it.                   H2SO4  =  ______ g/mole

                                    2 x H = 2 x ______g   =    ______g  

                                    1 x S = 1 x ______g    =    ______g  

                                    4 x O = 4 x_______g    =   ______g  

 

54. 6.02 x 1023 is called Avogadro’s number and is the number of particles in 1 mole of a substance.

Equal volumes of gases contain an equal number of molecules.

            Under similar conditions, which sample contains the same number of moles of particles

as 1 liter of O2 (g)?

1 L Ne(g)         0.5 L SO2 (g)                2 L N2 (g)                      1 L H2O(l)