Law of the Conservation of Mass

• Natuurkunde / Scheikunde
• Middelbare school
• vwo
• Leerjaar 2

Chemical reactions (1)

• reactants are changed into reaction products
• the properties of matter have changed
• there is always an energy effect
• the total mass of the reactants equals the total mass of the reaction products
• a minimum reaction temperature is always needed

What determines the mass of an atom?

1. protons and electrons
2. The protons and neutrons
3. The protons and Neutrons
4. It's atomic number

What is the atomic mass of this atom?

1. 7 u
2. 14 u
3. 21 u
4. 28 u

What is the Law of Lavoisier?

• It is the law of conservation of mass. 
• In a chemical reaction, the total mass of the reactants equals the total mass of the reaction products.

Law of Lavoisier

3 grams of hydrogen reacts with 

24 grams of oxygen and becomes

27 grams of water.

3g + 24g = 27 g

What meant Lavoisier with conservation of mass?

energy effect

Exothermic reactions transfer energy to the surroundings 

the temperature of the surroundings increases. 

Endothermic reactions take in energy 

the temperature of the surroundings decreases.

Reaction temperature (or activation temperature) is the minimum temperature for a chemical reaction.
 

Let's count the mass

assignments today:

first:   B3, B4, B5

then: B9, B10

when finished: choose to watch video 1 again, or B11 and C16