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In GCSE Chemistry , the concept of moles is crucial for mastering chemical equations and stoichiometry. The mole is a fundamental unit that allows chemists to relate atomic and molecular quantities to measurable amounts of substances. One mole of any substance contains Avogadro’s number (6.022 × 10²³) of particles, whether they are atoms, molecules, or ions. The Relationship Between Mass, Moles, and Molar Mass To calculate the number of moles (n) in a substance, we use the following formula: n=Mass (g)Molar Mass (g/mol)n = \frac{Mass\ (g)}{Molar\ Mass\ (g/mol)} where: Mass is the quantity of the substance in grams, Molar mass is the relative atomic or molecular mass of the substance (found in the periodic table). For example, the molar mass of water ( H₂O ) is calculated as: (2×1.0)+(1×16.0)=18.0g/mol(2 \times 1.0) + (1 \times 16.0) = 18.0 g/mol So, 9g of water contains: n=918=0.5 molesn = \frac{9}{18} = 0.5 \text{ moles} Balanced Chemical Equations and Mole Ratios Balanced chemical ...

  Algebra is a fundamental part of mathematics that helps us understand patterns, relationships, and problem-solving. It may seem challenging at first, but with the right approach, you can master it step by step. This guide is designed to help KS3 students build a strong foundation in algebra. 1. What is Algebra? Algebra is a branch of mathematics that uses symbols, letters, and numbers to represent relationships and solve equations. Instead of just working with numbers, algebra introduces variables (letters like xx and yy) that can stand for unknown values. For example: Instead of writing 2 + 3 = 5 , we might write x+3=5x + 3 = 5 and solve for xx. 2. Basic Algebraic Terms Before diving into solving problems, it’s important to understand some key terms: Variable : A letter (e.g., x,y,a,bx, y, a, b) used to represent a number. Constant : A fixed number (e.g., 2, 5, -7). Coefficient : A number multiplying a variable (e.g., in 3x3x, the coefficient is 3). Expression : A combination o...