How does propulsion work?
All rockets get thrust by propelling fuel of of themselves, so the amount of fuel that goes up into space is important to the amount of thrust the rocket is to have. Because every drop of fuel and oxidizer that goes up into space adds mass and weight to the spacecraft, scientists want to have exactly enough fuel to do what they want and no extra. They also want the ship to have equal amounts of fuel and oxidizers when using a fuel that combines the two.
Scientists know about the chemical reactions that will occur when the fuel and oxidizer combine, so they know exactly what the proportion of fuel to oxidizer should be. In order to get the right proportions, scientists use the molecular formulae of the fuels of rockets to figure out how many moles of fuel they need. Once they know how many moles of fuel they need, they can calculate the appropriate mass of fuels.
What is a propellant?
How do conventional rockets work?
What is thrust?
What would happen if DS1 ran out of fuel?
What are some rocket propellants?
How do things burn?
What is an oxidizer?
Why is mass important?
What is mass?
What is a mole?