Empiracal & molecular formula

When phosphorus is burnt in a free supply of air, diphosphorous pentoxide is formed. During later stages of combustion in a limited supply of air, the flame becomes larger greenish and flickering. Another phosphorus oxide is formed which is a white waxy crystalline solid which melts @ 23.8 degrees C and becomes a gas @ 176 degre ...continues

dry hydrogen selenide

see attachment 1

electrochemistry: mass and charge equations

Electrochemistry can be used to measure electric current in a silver coulometer. The cathode is weighed before and after the passage of the current. A silver cathode initially has a mass of 10.77 grams and its mass increases to 12.89 grams after current has flowed for 15.0 minutes. Compute the quantity of charge in coulombs a ...continues

Chemical formula, Gas volume

See Attachment The composition of hydrogen selenide (H2Se) can be determined by heating tin (Sn) in a measured volume of the gas. The hydrogen selenide is decomposed, producing solid tin selenide (SnSe) and hydrogen gas. If the temperature and pressure are unchanged, the gas volume when the decomposition is over is the sa ...continues

Half life and chemical reaction problems

A radioactive isotope of mass number 94 has been prepared by neutron bombardment. If 4.7 ug (1 ug = x 10 ^-6 g) of this isotope registers 20 counts per minute on a radioactivity counter, what is the half life of this isotope?

electron configurations

How would I find/identify the expected electron configuration for: Cr3+, Au3+, Ru2+ Cu+, Mn4+, and Ir3+?

Atomic number and full symbol of unknown element

An unknown element which has 120 protons and 174 neutrons, has the name ultimatum and symbol Ul. Give the atomic number of ultimatum and give the full symbol for the above isotope.

half life equations

Some estimates give t1/2 = 1100 s, but more refined experiments give t1/2 = 876 + or - 21 s. Suppose a neutron source generates 10^5 neutrons per second for 30 seconds. Assuming no neutrons are captured by nuclei, how many will be left after 5 hours according to each of these half lives?

Compute the energy released in joules per event and in kilojoules per mole when antiprotons annihilate with protons.

Compute the energy released in joules per event and in kilojoules per mole when antiprotons (the antimatter corresponding to protons) annihilate with protons. An antiproton has the same mass as a proton. Equation: 1 H + 1 H > energy

metal heating

Given that: Initial temperature of metal: 20c Final temperature of metal: 100c Initial temperature of water from calorimeter: 20c Final water temperature from calorimeter: 28c 1. What is estimate of specific heat for metal?: (use 1 cal/gm-°C for water) 2. What is estimate the atomic weight of metal?: