Is freezing water a physical or chemical change

The reaction between hydrogen and oxygen to yield water vapor has ΔH∘=-484kJ: 2H2 (g) + O2 (g) →2H2O (g) ΔH∘=-484kJ How much PV work is done in kilojoules for the reaction of 3.20 mol of H2 with 1.

What happens when light strikes an opaque object? A) All of the light passes through the object. B) All of the light is reflected by the object. C) None of the light passes through the object.

You have two solutions, both with a concentration of 0.1M. Solution A contains a weak acid with a pKa of 5. The pH of solution A is 3. Solution B contains a weak acid with a pKa of 9. The pH of solution B is:

Read the given equation. Na2O2 + CO2 → Na2CO3 + O2 What volume of O2 gas is produced from 4.60 liters of CO2, assuming all values are measured at STP? 1.20 liters 2.30 liters 5.20 liters 9.20 liters

The equation below describes a reaction between an acid and a base. What is missing from the equation? H2SO4 + NaOH? Na2SO4 A. water B. a salt C. the acid D. the base

A neutral atom has an atomic number of 20 and a mass number of 41; how many protons, neutrons, and electrons are found within the atom?

Which of the following are dwarf planets Ceres Nama is Eris Charon Haumea Makemake Pluto

Which set of factors changes igneous or sedimentary rock into metamorphic rock? heat and weathering water and weathering heat and pressure water and pressure

What is the standard cell potential (E°cell) for the voltaic cell based on the reaction below? Sn2 + (aq) + 2Fe3 + (aq) → 2Fe2 + (aq) + Sn4 + (aq)

G oil of wintergreen, c8h8o3 is prepared when methanol, ch3oh, is reacted with salicylic acid, c7h6o3. what is the percent yield of a reaction in which 15.3 g of oil of wintergreen is collected after 16.