Conservation of Mass and Balancing Equations

Balance this equation-
__P₄ + __O₂ --> __P₂O₃

• it is already balanced

• 2, 1, 3

• 1, 2, 3

• 1, 3, 2

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NGSS.MS-PS1-5

Balance this equation.
_CF₄ + _Br₂ -- _CBr₄ + _F₂

• 2,1,2,1

• 1,2,2,1

• 1,2,1,2

• 2,2,2,2

Tags

NGSS.MS-PS1-5

10 g of a solid chemical reacts with a 10 g of a liquid chemical, the reaction bubbles and changes the color of the liquid.  The colored liquid weighs 13 g, what can be concluded?

• The gas produced from the bubbles weighed 5 g

• The bubbles were evidence of 7 g of matter being destroyed

• The gas produced weighed 7 g

• The gas produced weighed 13 g

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

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.  

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How does the Law of Conservation of Mass apply to a burning candle?

• The amount of wax before the reaction equals the amount of energy afterwards.

• The mass of the wick before the reaction equals the mass of the smoke afterwards.

• The mass of the wick, wax that burned and the oxygen that helped the flame before the reaction equals the mass of the smoke and the gases released after the reaction.

• The mass of the molecules of the candle before the reaction equals the mass of the candle and burned wick after the reaction.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

Tags

NGSS.MS-PS1-5

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit

• Invisible

• Transformed, changed

• None of the above

Tags

NGSS.MS-PS1-5

If a reaction starts with a total 75g of reactants it should produce 

• a total of 40g of products

• a total of 75g of products

• a total of 180 g of products

• None of the above

Tags

NGSS.MS-PS1-5

In the reaction AB-----> A + B reactant AB has 12g and product B has 5g. How many grams should product A have?

• 17g

• 2g

• 7g

• None of the above

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5