What is the molar (M) concentration of phosphate ions (PO43-) in a 725 mL solution containing 155 grams of lead(III) phosphate, Pb3(PO4)4? Molar mass of Pb3(PO4)4 is 1001.4 g/mol

Calculate the ∆H°rxn for the combustion of methane using the given ∆H°f. CH4 (g)  +  2O2(g)  → CO2(g) + 2H2O(l) ∆H°f, methane(g) = -74.60 kJ/mol ∆H°f, water(l) = -285.8 kJ/mol ∆H°f, carbon dioxide(g) = -393.5 kJ/mol

Determine the oxidation number of sulfur (S) in thiosulfate polyatomic ion, S2O32−.

Calculate the ∆H°rxn for the combustion of methane using the given ∆H°f. CH4 (g)  +  2O2(g)  → CO2(g) + 2H2O(l) ∆H°f, methane(g) = -74.60 kJ/mol ∆H°f, water(l) = -285.8 kJ/mol ∆H°f, carbon dioxide(g) = -393.5 kJ/mol

Every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin

A mixture of Ar and Kr at a total pressure of 1.20 atm contains 0.30 mol of Ar and 0.70 mol of Kr. What is the partial pressure of Kr in atm?

Use the Lewis dot structure (make sure you show all electron pairs) and VSEPR theory to predict the molecular geometry and bond angle in the ammonium ion NH4+. Hint: Use the table below to answer the question.   VSEPR quick reference: electron groups, shapes, and approximate bond angles Electron Groups Bonding Groups Lone Pairs Electron Geometry Molecular Geometry Approximate Bond Angles 2 2 0 Linear Linear 180° 3 3 0 Trigonal planar Trigonal planar 120° 3 2 1 Trigonal planar Bent

The limiting reagent (reactant) in a chemical reaction is one that:

A piece of aluminum with a mass of 55.0 g has an initial temperature of 95.0°C. The aluminum is immersed in a beaker containing an unknown mass of water at 21.0°C. When they reach thermal equilibrium, the final temperature is 28.5°C. What is the mass of the water, g? (Specific heat of Al = 0.903 J/g·°C; Specific heat of H2O = 4.184 J/g·°C)

Give the number of valence electrons for HSO4-.