Fundamental Chemistry Review NTI#15 (CHEM)

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction

• Mass is created in a physical change

• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants

• Mass is never created or destroyed

In a reaction A + B ----> C, reactant A has 5g and product C has 9g. How many grams does reactant B should have?

• 4g

• 5g

• 9g

• 14g

Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?

• 200 g

• 700 g

• 1,100 g

24 g of magnesium reacts with 38 g of fluorine to produce _____ g magnesium fluoride

• 62

• 38

• 24

• 14

Students react baking soda & vinegar.

Which of the following would provide the evidence that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction?

• The mass of the plastic bag, baking soda, and vinegar before the reaction was equal to the mass after the reaction.

• Bubbles were produced during the reaction, which meant that a gas was being produced.

• The plastic bag did not change in any way, indicating that it was not involved in the reaction.

• The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.

Suppose a reaction were to happen in an open container in a lab. During the reaction, the scientist observes the chemicals bubble, and produce a gas. During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g. Explain what happened.

• His chemical reaction defied the law of conservation of mass

• The product destroyed mass during the reaction

• The reactants created matter during the reaction

• The gas that was produced was not able to be weighed since the container was open.

This particle determines what element you have - the elements identity.

• electron

• proton

• neutron

• valence shell

This causes the mass of the nucleus to increase.

• adding an electron

• adding a neutron

• more orbitals

• adding negatively charged particles

What is the mass number and name of an element with 8 protons and 8 neutrons?

• 16 - Carbon

• 16 - Oxygen

• 24 - Oxygen

• 8 - Neon

An atom has 10 protons, 15 neutrons and 10 electrons what is its mass number.

• 20

• 10

• 5

• 25