A 3.0-L sample of helium was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 24 hours. A 3.0-L sample of oxygen was placed in an identical container. How many hours will it take for half of the oxygen to effuse through the membrane?
A 50.0 mL solution of sodium chloride, NaCl (58.44 g/mol), weighing 50.320 g, is evaporated to dryness. If the white solute residue has a mass of 0.453 g, what is the mass/mass percent concentration and molarity of the saline solution?
Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction:<img src="https://sciemce.com/files/4/ppg__mchem5tbb0212192104__f24g1q44g1.jpg" alt="" style="vertical-align: -7.0px;" />
Classify the following type of stoichiometry problem: How many grams of cobalt must react with an excess volume of hydrochloric acid to produce 25.0 mL of hydrogen gas?
A solution contains Co2+, Ba2+, Ag+, NH4+, and Cd2+. Identify the precipitate after the addition of 6 M HCl; then H2S and 0.2 M HCl; then OH- to a pH of 8; and then (NH4)2HPO4 with NH3.
Which of the following structures has a different configuration from the other three? <img src="https://sciemce.com/files/4/ppg__tttt0821191047__f1q325g1.jpg" alt="" style="vertical-align: 0.0px;" height="136" width="550" />
When atoms of beryllium-9 are bombarded with alpha particles, neutrons are produced. What new isotope is also formed? <img src="https://sciemce.com/files/4/ppg__1270822190923__f1q11g1.jpg" alt="" style="vertical-align: 0.0px;" height="29" width="200" />
Using the bond enthalpies tabulated below, calculate the enthalpy of reaction for the combustion of hydrogen. Hint: the bond enthalpies are approximate enthalpies needed to make or break a chemical bond. 2H2(g) + O2(g) ® 2H2O(g)
bondDH (kJ) H-H436 O-H464 O-O138 O=O498
Consider the following reaction: Xe(g) + 2 F2(g) ⇌ XeF4(g) A reaction mixture initially contains 2.24 atm Xe and 4.27 atm F2. If the equilibrium pressure of Xe is 0.34 atm, find the equilibrium constant (Kp) for the reaction