Chemistry

Atoms, elements, substances, reactions, calculations and transformations of matter explained with examples.

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Bancada de química com modelos moleculares, vidrarias e lousa exibindo a equação 2 H₂ + O₂ → 2 H₂O e uma tabela de contagem de átomos.

Chemistry22/09/20266 min read

Balancing chemical equations: how to adjust coefficients without changing formulas

Learn to balance chemical equations by preserving formulas, counting atoms, and changing only coefficients, with worked examples that increase in difficulty.

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Bancada de laboratório com pipeta, béqueres, balão volumétrico e proveta com soluções azuis, acompanhados da equação C1V1=C2V2 e indicações de unidades.

Chemistry14/09/20267 min read

Dilution without memorizing: how to use C1V1=C2V2, get the units right, and know when it does not apply

Understand where C1V1=C2V2 comes from, how to check units and final volume, solve three common problem types, and recognize situations where the dilution equation does not apply.

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Bloco de gelo flutuando na água, com parte submersa e dois detalhes moleculares mostrando a rede hexagonal aberta do gelo e moléculas mais compactas na água líquida.

Chemistry13/09/20266 min read

Why Does Ice Float? Hydrogen Bonds, Water Expansion, and Density

Learn why water expands when it freezes, how hydrogen bonds create an open lattice, and why that structure makes ice less dense than liquid water.

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Tigela de vidro com cubos de gelo recebendo sal grosso, com pote de sal, colher de madeira e termômetro sobre uma mesa.

Chemistry12/09/20265 min read

Why salt melts ice and the mixture drops below 0 °C

Learn how freezing-point depression lets an ice-salt mixture fall below 0 °C, with a simple experiment, an approximate calculation, and the limits of the ideal model.

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