According to the law of conservation of mass, mass cannot be gained or destroyed in a chemical reaction. Why can't you simply add the masses of two reactants to determine the total mass of product?

Short Answer

Expert verified
The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction, meaning the total mass of reactants should equal the total mass of products. Simply adding the masses of two reactants to determine the total mass of products is incorrect because it does not consider the stoichiometry of the reaction, which dictates the proportions of reactants used and products formed. To determine the correct mass of products, we must follow a series of steps involving the balanced chemical equation, molar conversions, identifying limiting reactants, and using stoichiometric coefficients to relate reactants and products. This approach ensures mass conservation in a chemical reaction.

Step by step solution

01

Introduction to the law of conservation of mass

The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction. In other words, the total mass of the reactants in a chemical reaction should be equal to the total mass of the products.
02

Understanding chemical reactions

In a chemical reaction, reactants are converted into products through the rearrangement of atoms, which involves breaking the existing bonds and forming new ones. It is essential to understand that the mass of atoms involved in a chemical reaction does not change; only the way they are connected or bonded changes.
03

Mismatch in mass while adding reactants

When we attempt to simply add the masses of the reactants to determine the total mass of products, we often find that there is a mismatch in the mass. This is because we are not taking into account the stoichiometry of the reaction, which is the balanced chemical equation that shows in what proportions the reactants are to be used exactly and how many products are formed. The stoichiometric coefficients in the balanced chemical equation play an essential role in how to obtain the correct mass of the products by relating the amount of reactants to the amount of products.
04

Stoichiometry and conservation of mass

By taking into account the stoichiometry of the reaction, we can properly understand the conservation of mass. To calculate the mass of the products, we need to follow these steps: 1. Write the balanced chemical equation for the reaction. 2. Convert the masses of the reactants into moles by dividing the masses by their respective molar masses. 3. Determine the limiting reactant (if there is one) by comparing the mole ratios of the reactants to their stoichiometric coefficients. 4. Calculate the moles of products formed by using the stoichiometric coefficients and the moles of limiting reactant. 5. Convert the moles of products into mass by multiplying them by their respective molar masses. Following these steps can help us understand the relationship between the masses of reactants and products and how they are related by the stoichiometry of the reaction. This will correctly show that the mass is conserved during a chemical reaction.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The molecular formula of acetylsalicylic acid (aspirin), one of the most commonly used pain relievers, is \(\mathrm{C}_{9} \mathrm{H}_{3} \mathrm{O}_{4}\). a. Calculate the molar mass of aspirin. b. A typical aspirin tablet contains \(500 . \mathrm{mg} \mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4} .\) What amount (moles) of \(\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}\) molecules and what number of molecules of acetylsalicylic acid are in a \(500 .-\mathrm{mg}\) tablet?

Several important compounds contain only nitrogen and oxygen. Place the following compounds in order of increasing mass percent of nitrogen. a. NO, a gas formed by the reaction of \(\mathrm{N}_{2}\) with \(\mathrm{O}_{2}\) in internal combustion engines b. \(\mathrm{NO}_{2}\), a brown gas mainly responsible for the brownish color of photochemical smog c. \(\mathrm{N}_{2} \mathrm{O}_{4}\), a colorless liquid used as fuel in space shuttles d. \(\mathrm{N}_{2} \mathrm{O}\), a colorless gas sometimes used as an anesthetic by dentists (known as laughing gas)

When the supply of oxygen is limited, iron metal reacts with oxygen to produce a mixture of \(\mathrm{FeO}\) and \(\mathrm{Fe}_{2} \mathrm{O}_{3} .\) In a certain experiment, \(20.00 \mathrm{~g}\) iron metal was reacted with \(11.20 \mathrm{~g}\) oxygen gas. After the experiment, the iron was totally consumed, and \(3.24 \mathrm{~g}\) oxygen gas remained. Calculate the amounts of \(\mathrm{FeO}\) and \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) formed in this experiment.

Dimethylnitrosamine, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{~N}_{2} \mathrm{O}\), is a carcinogenic (cancercausing) substance that may be formed in foods, beverages, or gastric juices from the reaction of nitrite ion (used as a food preservative) with other substances. a. What is the molar mass of dimethylnitrosamine? b. How many moles of \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{~N}_{2} \mathrm{O}\) molecules are present in \(250 \mathrm{mg}\) dimethylnitrosamine? c. What is the mass of \(0.050\) mol dimethylnitrosamine? d. How many atoms of hydrogen are in \(1.0 \mathrm{~mol}\) dimethylnitrosamine? e. What is the mass of \(1.0 \times 10^{6}\) molecules of dimethylnitrosamine? f. What is the mass in grams of one molecule of dimethylnitrosamine?

Phosphorus can be prepared from calcium phosphate by the following reaction: \(2 \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}(s)+6 \mathrm{SiO}_{2}(s)+10 \mathrm{C}(s) \longrightarrow\) $$ 6 \mathrm{CaSiO}_{3}(s)+\mathrm{P}_{4}(s)+10 \mathrm{CO}(g) $$ Phosphorite is a mineral that contains \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) plus other nonphosphorus- containing compounds. What is the maximum amount of \(\mathrm{P}_{4}\) that can be produced from \(1.0 \mathrm{~kg}\) of phosphorite if the phorphorite sample is \(75 \% \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) by mass? Assume an excess of the other reactants.

See all solutions

Recommended explanations on Chemistry Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free