# Chapter 7-8

 Avogadro's number 6.02X10^23 How many particles of substance is contained in any mole? 6.02X10^23 What is equal to the atomic weight in grams of any element it's equal to 1 mole of atoms convert 25.0g of iron to moles if the atomic weight of iron is 44.85 (g of Fe)=(1 mol Fe)/(55.85g Fe)=0.448 mol Fe What is the  percent composition mass percent of each element in the compound How do you balance an equation? •To balance an equation, adjust the number of atoms of each element so that they are the same on each side of the equation. Coefficients only, not the subscripts What is placed in front of the substance to balance the equation to indicate the number of units (atoms, molecules, moles, or ions)? coefficients or whole numbers Why would a symbol be placed above or below the arrow while balancing an equation? to show a condition required for reaction (like heat). (l), (g), (s) on the bottom right of a symbol would indicate that it is in the physical state of being a liquid, gas, or solid. symbol meaning and location + means plus, placed between substances. ↔ means resonance,placed between substances → means yieldsplaced between reactant and product right half arrow above left pointing half arrow equilibrium,placed between reactants and products (aq) aqueousafter formula ∆ heatwritten above arrow hv light energy, written above arrow ↑ gas formationafter formula ↓ precipitate formationwritten after formula which side of the  balanced equation are reactants and products written? reactants are on the left, and products are on the right. Types of chemical equations 1) combination (synthesis)2)combustion (analysis)3) decomposition (substitution)4) single displacement (metathesis) 5) double displacement (oxidation) Example of oxidation Metal and oxygen Example of single/double displacement reaction one/+ element in a compound is exchanged with another element in another compound. example of combustion Hydrocarbon reacts with oxygen to produce carbon dioxide and water. Authorstudysuccess ID185224 Card SetChapter 7-8 Descriptionchapter 7-8 Updated2012-11-25T08:39:54Z Show Answers