Iron comes from Iron Ore via the Forge. Iron Ore can be found in Iron Nodes in the Stalactite layer and Lava layer. The ore has to be harvested with an Extractor, as the node itself cannot be pulled with Power Cells, it also cannot be placed. All Ores can be smelted into bars in a Forge for further processing.
It depends on the substance (water for example has 1000 grams to a liter, other substances have more grams or less grams to a liter depending on a property (called the density measured in grams / liter) of the substance.
Stoichiometry: Moles to Liters. To convert between moles and liters you need to remember that one mole of a gas occupies 22.4 liters. Method 1 (watch video tutorial): Use the conversion factor: 1 mol gas = 22. 4L. Method 2: (watch video tutorial) When going from moles to liters you multiply by 22.4. When going from liters to moles you divide by 22.4.