Quantitative chemistry

Question 1

Why must equations be balanced

Answer 1

Because no atoms are lost or joined in a chemical reaction. Instead atoms join together in different ways to form products. This is why, in a balanced symbol equation, the number of atoms of each element is the same on both sides of the equation

Question 2

How could substances leave a non-enclosed system

Answer 2

These systems include open flasks, boiling tubes or crucibles that let gases enter or leave.

Question 3

How could substances leave a non-enclosed system

Answer 3

These systems include open flasks, boiling tubes or crucibles that let gases enter or leave.

Question 4

Limiting reactants defi

Answer 4

The reactant that is all used up is called the limiting reactant

Question 5

What do you call the reactant that is left over is described as being in _____

Answer 5

excess

Question 6

A reaction has finished when

Answer 6

When one of the reactants is all used up.

Question 7

Percentage by mass of an element = ???

Answer 7

(Total relative atomic mass of the atoms of that (element
(—————————————————————-)
Relative formula mass of compound)

Question 8

Avogadro’s law states

Answer 8

When temperature and pressure stay the same

There are equal volumes of different gases contain and equal number of molecules

Question 9

Hydrogen reacts with oxygen to produce steam:

2H2(g) + O2(g) → 2H2O(g)

Calculate the volume of steam that can be produced from 50 cm3 of oxygen and an excess of hydrogen.

Answer 9

The mole ratio of oxygen to steam is 1:2

Volume of steam = 50/1 * 2

Volume = 100 cm