Conservation of Mass Flashcards
Quantitative Chemistry (18 cards)
What happens to atoms during a chemical reaction?
No atoms are destroyed and no atoms are created.
What does it mean for mass to be conserved in a chemical reaction?
There are the same number and types of atoms on each side of a reaction equation.
What is the total mass before and after a chemical reaction?
No mass is lost or gained; mass is conserved during a reaction.
In the reaction 2Li + F2 -> 2LiF, how many lithium and fluorine atoms are on each side?
2 lithium atoms and 2 fluorine atoms on each side.
How do you demonstrate that mass is conserved in a reaction?
By adding up the relative formula masses of the substances on each side of the equation.
What is the relative formula mass calculation for the left-hand side of the equation 2Li + F2?
2 x M(Li) + 2 x M(F) = (2 x 7) + (2 x 19) = 52.
What is the relative formula mass calculation for the right-hand side of the equation 2LiF?
2 x M(LiF) = 2 x (7 + 19) = 52.
What indicates that mass is conserved in a chemical reaction?
The total mass on the left-hand side equals the total mass on the right-hand side.
True or False: A change in mass during an unsealed reaction vessel always indicates a chemical reaction.
False.
What is a possible explanation if the mass of an unsealed reaction vessel increases?
One of the reactants is a gas found in air, like oxygen.
What could cause a decrease in mass in an unsealed reaction vessel?
One of the products is a gas escaping from the reaction vessel.
What happens to gas before a reaction in an unsealed vessel?
The gas is floating around in the air and is not contained in the reaction vessel.
What occurs when a gas reacts to form part of a product in an unsealed vessel?
The gas becomes contained inside the reaction vessel.
In the example of a metal carbonate decomposing, what happens to the mass of the reaction vessel if it isn’t sealed?
The mass of the reaction vessel will decrease.
In a metal reaction with oxygen in an unsealed container, what happens to the mass?
The mass of the container increases.
Fill in the blank: The mass of the metal oxide produced equals the total mass of the _______.
metal and oxygen that reacted from the air.
What does the particle model say about gases?
A gas will expand to fill any container it is in.
What happens to gas if the reaction vessel isn’t sealed?
The gas expands out from the vessel and escapes into the air.
