Expert Chemistry Tutoring

MS1.

- Mass is neither created nor destroyed in a chemical reaction (1)

MS2.

- Oxygen reacts with fuels to form new compounds (1)

- These new compounds are more oxidized than the fuels (1)

MS3.

- Moles of methane = (24 / 16) mol = 1.5 mol (1)

- Moles of carbon dioxide produced = 1.5 mol (from balanced equation) (1)

- Mass of carbon dioxide = (1.5 mol × 44 g/mol) = 66g (1)

MS4.

- The mass of the reactants in a chemical reaction is equal to the mass of the products (2)

MS5.

- The observation is incorrect (1)

- According to the law of conservation of mass, the mass of the reactants should be equal to the mass of the products (1)

- There may be errors in measuring the masses (1)

MS6.

- Correctly identifies that Fe needs to be multiplied by 2 (1)

- Correctly balances oxygen by adding coefficient 3 to O2 (1)

MS7.

- To prevent gases or liquids from escaping, which would alter the mass of the system (2)

MS8.

- A chemical reaction that releases heat into the surroundings (1)

MS9.

- Identifies that the reaction involves the decomposition of a carbonate, which is usually an endothermic process (1)

- Predicts that the reaction is endothermic (1)

MS10.

- Mass before and after the reaction should be the same (1)

- If the container is not sealed, gases (e.g., NO2) could escape and alter the mass (1)