Why is changing the subscripts in a chemical formula, such as turning $\mathrm{H}_2\mathrm{O}$ into $\mathrm{H}_2\mathrm{O}_2$ , an incorrect way to balance an equation?

In the balanced equation for the combustion of methane:

\mathrm{CH}_4 + 2\mathrm{O}_2 \rightarrow \mathrm{CO}_2 + 2\mathrm{H}_2\mathrm{O}

True or False: The coefficients in a balanced chemical equation represent the relative mass of each reactant and product in grams.

True or False: In a balanced chemical equation, the ratio of the masses of the reactants is always identical to the ratio of their coefficients.

When converting from the mass of a reactant to the mass of a product, why is the 'mole ratio' from the balanced equation considered a necessary 'bridge'?

MYP MYP Chemistry Topic Balancing Equations Questionbank

Practice MYP MYP Chemistry Topic Balancing Equations with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for Balancing Equations and mirrors Paper 1, 2 style where relevant.

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CO2+

2H2O

What is the specific ratio of oxygen molecules consumed to carbon dioxide molecules produced?

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It changes the chemical identity of the substance

Subscripts must always be even numbers

It violates the law of gravity

It makes the equation too long

True

False

True

False

Because mass is not conserved in chemical reactions

Because molar mass is the same for all substances in a balanced equation

Because the law of conservation of mass only applies to moles

Because coefficients represent ratios of particles or moles, not direct ratios of mass in grams

1:2

1:1

2:1

2:2