energy is required to move from one state or phase of matter to the next. Energy is used to make a liquid into a gas or a solid into a liquid.
MgCl₂(aq) + 2LiOH(aq) = Mg(OH)₂(s) + 2LiCl(aq)
Mg²⁺ + 2Cl⁻ + 2Li⁺ + 2OH⁻ = Mg(OH)₂ + 2Li⁺ + 2Cl⁻
Mg²⁺ + 2OH⁻ = Mg(OH)₂ <span>the net ionic equation</span>
<span>Mass percentage is one way of representing the concentration of an element in a compound or a component in a mixture. </span>To calculate percent by mass, you need to determine two things: the mass of just the element, and the molar mass of the whole compound. We calculate as follows:
.10 g NaCl / g NaCl + Water = ( 10.0 g NaCl + x ) / (10.0 g + 255 g + x )
x = 18.33 g NaCl needed
Assuming that we are given the values of Ka and Kb, these can be rewritten and represented by the concentration of the Hydronium ion and Hydroxide Ion:
Hydronium ion: [H3O+]
Hydroxide ion: [OH-]
Ka is the equilibrium constant of an acid which dissociates to a hydronium ion and its cation.
Kb is the equilibrium constant of a base which dissociates to a hydroxide ion and its anion.
So,
Ka x Kb = [H3O+][OH-]
Radio waves. A cell phone transmits its signal to the towers by <em>electromagnetic waves</em>.
The electromagnetic waves are in the <em>radiofrequency region</em> of the electromagnetic spectrum.
Most cell phones in North America use radiofrequencies between <em>700 MHz and 850 MHz</em> and between <em>1700 MHz and 2500 MHz</em>.