CHAPTER 6. QUANTITATIVE ASPECTS OF CHEMICAL CHANGE 6.8
Exercise 6 - 8
- Diborane, B 2 H 6 , was once consideredfor use as a rocket fuel. The combustion reaction for
diborane is:
B 2 H 6 (g) + 3O 2 (g)→ 2 HBO 2 (g) + 2H 2 O(�)If we react 2.37 grams of diborane, how many grams of water would weexpect to produce?- Sodium azide is a commonly used compound in airbags. When triggered, it has the following
reaction:
2 NaN 3 (s)→ 2 Na(s) + 3N 2 (g)If 23.4 grams of sodiumazide is used, how many moles of nitrogen gaswould we expect to
produce?- Photosynthesis is a chemical reaction that isvital to the existence oflife on Earth. During pho-
tosynthesis, plants and bacteria convert carbon dioxide gas, liquid water,and light into glucose
(C 6 H 12 O 6 ) and oxygen gas.
(a) Write down the equation for the photosynthesis reaction.
(b) Balance the equation.
(c) If 3 moles of carbon dioxide are used upin the photosynthesis reaction, what mass of
glucose will be produced?More practice video solutions or help at http://www.everythingscience.co.za(1.) 00z4 (2.) 00z5 (3.) 00z6Chapter 6 — Summary
See the summary presentation ( Presentation: VPjgr at http://www.everythingscience.co.za)- It is important to be able to quantify the changes that take place duringa chemical reaction.
- The mole (n) is a SI unit that is usedto describe an amount of substance that contains the same
number of particles as there are atoms in 12 g ofcarbon. - The number of particles in a mole is called the Avogadro constant and its value is 6.022× 1023.
These particles could beatoms, molecules or other particle units, depending on the substance. - The molar mass (M) is the mass of one moleof a substance and is measured in grams per mole
or g.mol−^1. The numerical valueof an element’s molar mass is the same as its atomic mass.
For a compound, the molar mass has the samenumerical value as themolecular mass of that
compound. - The relationship between moles (n), mass in grams (m) and molar mass (M) is defined by the
following equation:
n =
m
M