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Predict the chemical formula of the precipitate that forms from the double displacement reaction between calcium nitrate and sodium carbonate.

An unknown substance has a mass of 6.440 g. The unknown substances is placed in a graduated cylinder containing 1.50 mL of water. When the substance is added to the cylinder the volume increases to 3.53 . What is the density of the unknown substance ?

4.29

1.28

3.17

1.82

The transition of an electron from n= 1 to n=3 can result in the emission of light.

The energy of electromagnetic radiation with a λ = 254 nm is greater than that with a λ= 1200 nm.

A balloon contains 0.25 moles of nitrogen and 0.72 moles of neon. If the total pressure in the balloon is 1.5 atm, what is the partial pressure of nitrogen?

A sample of nitrogen gas in a 2.25 L container exerts a pressure of 755 Torr at 25°C. What is new the pressure of the gas if the volume of the container is decreased to 1.25 L and the temperature is raised to 245°C?

H2 is produced by the reaction of 118.5 mL of a 0.8775-M solution of H3PO4 according to the following equation:

 Cr (s) + H3PO4 (aq)→ H2 (g) +CrPO4 (aq)

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Balance the chemical equation and determine the number of moles of H2 produced.

4NH3(g)+5 O2(g)→4NO(g)+6H2O(l)

1. Identify the oxidation of each element on the reactant side.

2. Identify the oxidation state of each element on the product side.

3. What is oxidized, what is reduced?

4. What is the oxidizing agent, what is the reducing agent?

Precipitation (double displacement)

Oxidation-Reduction

Combustion

Acid-Base (neutralization)

1.    2CH3OH(l)+3O2(g)→2CO2(g)+4H2O(g)

2.    Fe (s) + O2 (g) → Fe2O3 (s)

3.    2FeBr3(aq)+3Ba(OH)2(aq)→2Fe(OH)3(s)+3BaBr2(aq)

4.    HBr(aq)+KOH(aq)→KBr(aq)+H2O(l)

4.    Calculate the average volume of NaOH needed to reach the equivalence point.

Average Volume to Reach the Equivalence Point: 25.00 mL

5.    Write the balanced chemical equation for the reaction between NaOH and HCl.

NaCl + H2O

6.    Use the information from Steps 4 and 5 to calculate the molarity of the HCl. Remember each trial used 25.00 mL of HCl.

0.3000 M NaOH is the concentration

4.    Calculate the average volume of NaOH needed to reach the equivalence point.

Average Volume to Reach the Equivalence Point: 25.00 mL

5.    Write the balanced chemical equation for the reaction between NaOH and HCl.

NaCl + H2O

6.    Use the information from Steps 4 and 5 to calculate the molarity of the HCl. Remember each trial used 25.00 mL of HCl.

for example Ag2 S Na+