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# check my chem ?

What is the concentration (Molar) when 1.039 moles of HBr are dissolved in 280 mL of water? (Give your answer to 3 significant figures).

= 3.71

How many grams of KBr are needed to make a 0.118 M solution of volume 750 mL? 3.71 (use masses K = 39.1, Br = 79.9 g/mol, give your answer to 3 significant figures)

= 3.71

Humpback whales can dive to 176 m depth where the pressure is 1.78 MPa. Assuming that the whales body temperature is constant (36.40 oC), what volume will the whales lungs now have? (Assume that the pressure at the surface is 1.000 atm or 101.3 kPa and the initial volume of the lungs is 3.600 x 103 L, give your answer to 3 significant figures, do not use scientific notation)

= 205

### 1 Answer

- jacob sLv 73 weeks ago
What is the concentration (Molar) when 1.039 moles of HBr are dissolved in 280 mL of water? (Give your answer to 3 significant figures).

M= moles/L

1.039 moles/ .280L = 3.71M

How many grams of KBr are needed to make a 0.118 M solution of volume 750 mL? (use masses K = 39.1, Br = 79.9 g/mol, give your answer to 3 significant figures)

0.118 M= 0.118 moles /L

0.118 moles (119g KBr/1 mole) = 14.0 g KBr

Humpback whales can dive to 176 m depth where the pressure is 1.78 MPa. Assuming that the whales body temperature is constant (36.40 oC), what volume will the whales lungs now have? (Assume that the pressure at the surface is 1.000 atm or 101.3 kPa and the initial volume of the lungs is 3.600 x 103 L, give your answer to 3 significant figures, do not use scientific notation)

According to Boyle's law, we know that, at constant temperature, pressure is inversely proportional to the volume of the gas.

Here, given that, temperature is constant.

Initial pressure, Pi = 101.3 kPa = 101300 Pa

Final pressure, Pi= 1.78 x 106 Pa

Initial volume, V = 3600 L

Therefore final volume is given by,

Vf=PiVi /Pf=3600Lx101300Pa/1.78x10^{6}Pa

..V = 204.88 L

Rounding to 3 significant figures,

:: Ve= 205 L

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