David's Science Review Part 2

Alexa is investigating various compounds. She has the chemical formulas for each compound.

What does the chemical formula help her know about each substance?

• 1. The chemical formula tells her that there has been production of a gas.

• 1. The chemical formula tells her that the compound underwent a color change.

• 1. The chemical formula tells her the type and number of atoms in the compound.

• 1. The chemical formula tells her the weight of each compound.

Tags

NGSS.MS-PS1-1

How does this chemical reaction demonstrate conservation of mass?

• 1. The number of carbon atoms is the same on both sides of the equation; the number of hydrogen and oxygen atoms decreases in the products.

• 1. The number of carbon, hydrogen, and oxygen atoms is different on both sides of the equation.

• 1. The number of carbon and hydrogen atoms is the same on both sides of the equation; the number of oxygen atoms increases in the products.

• 1. The number of carbon, hydrogen, and oxygen atoms is the same on both sides of the equation.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Taleah conducts a chemical reaction and wants to know the number of hydrogen atoms in the products. Hydrogen only appears in the compound 2H20 in the reactants.

How many hydrogen atoms must be in the products?

• 1. There must be 8 hydrogen atoms in the products, because mass increases from reactants to products.

• 1. There must be 4 hydrogen atoms in the products, because the total mass is conserved.

• 1. There must be 2 hydrogen atoms in the products, because the total mass is conserved.

• 1. There must be 6 hydrogen atoms in the products, because mass decreases from reactants to products.

Tags

NGSS.MS-PS1-5

Alexa is investigating various compounds. She has the chemical formulas for each compound.

What does the chemical formula help her know about each substance?

• 1. The chemical formula tells her that there has been production of a gas.

• 1. The chemical formula tells her that the compound underwent a color change.

• 1. The chemical formula tells her the type and number of atoms in the compound.

• 1. The chemical formula tells her the weight of each compound.

Tags

NGSS.MS-PS1-1

Rachel conducts the following reaction:

She uses 2 g of sodium (Na) and 3 g of chlorine (Cl2). How many grams of product would she produce?

• 1. 4 g, because each molecule of NaCl would have a mass of 2 g.

• 1. 10 g, because one compound of NaCl would have a mass of 5 g and the reaction produces two compounds of NaCl.

• 1. 5 g, because the number and type of atoms are the same before and after the reaction, so the mass in grams should also be the same.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Max is curious about what happens to the mass of iron nails when they rust. He puts some new iron nails in a jar, adds some water, and seals the jar tightly. He puts the jar in a closet where it is left undisturbed for 365 days. The observations of the jar on day 1 and day 365 are shown in the image.

The chemical formula for the formation of rust is given above

Define the conservation of mass and explain how it applies to the chemical equation and the image.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

A group of students conducts a chemical reaction during a lab. They mix two substances together in a closed system. During the reaction, they notice the temperature of the substances increases.

Would this increase in thermal energy change the mass of the products? Explain your answer.

Tags

NGSS.MS-PS1-5

In a chemical reaction, the atoms in the____________rearrange to form new__________. This is why the mass before the reaction_____________  the mass after the reaction.

• products; reactants; is greater than

• products; products; is less than

• reactants; products; is equal to

• reactants; reactants; is greater than

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

When people exercise, a chemical reaction occurs in the body. Cells conduct a reaction to break down sugar and use oxygen to generate energy. This reaction is shown in the following chemical equation:

Which of the following is true of the equation?

• 1. The number of atoms is more in the products than the reactants because energy is released in the products.

• The number of atoms is less in the products than the reactants because energy is produced in the products.

• 1. The number of atoms is the same in the reactants and the products; the atoms simply rearrange to form a    new substance.

• The number of atoms is less in the products than the reactants because energy is absorbed in the reaction.

Tags

NGSS.MS-PS1-5

Marsha is investigating the following chemical reaction:

She wants to use the equation to predict the mass of the products that will form. What does this equation indicate about the atoms before and after the reaction?

• 1. The mass of the products will be the same as the mass of the reactants because there will be 2 atoms of Al, 3 atoms of Cu, and 6 atoms of Cl before and after the reaction.

• 1. The mass of the products will be the same as the mass of the reactants because there will be 2 atoms of Al, 6 atoms of Cu, and 6 atoms of Cl before and after the reaction.

• 1. The mass of the products will be greater than the mass of the reactants because 2 atoms of Cl will change into 3 atoms of Cl in the products.

• 1. The mass of the products will be greater than the mass of the reactants because 2 atoms of Al in the reactants will change into 6 atoms of Al in the products.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2