When energy is needed in order for the reaction to happen, then that reaction is known as endotermic. When the reaction has as a result energy then it is exotermic. An example of an endotermic reaction would be photosynthesis, for an exotermic: combustion.
Answer:
Commonly available heat-storage materials cannot usually store the energy for a prolonged period. If a solid material could conserve the accumulated thermal energy, then its heat-storage application potential is considerably widened. Here we report a phase transition material that can conserve the latent heat energy in a wide temperature range, T<530 K and release the heat energy on the application of pressure. This material is stripe-type lambda-trititanium pentoxide, λ-Ti3O5, which exhibits a solid–solid phase transition to beta-trititanium pentoxide, β-Ti3O5. The pressure for conversion is extremely small, only 600 bar (60 MPa) at ambient temperature, and the accumulated heat energy is surprisingly large (230 kJ L−1). Conversely, the pressure-produced beta-trititanium pentoxide transforms to lambda-trititanium pentoxide by heat, light or electric current. That is, the present system exhibits pressure-and-heat, pressure-and-light and pressure-and-current reversible phase transitions. The material may be useful for heat storage, as well as in sensor and switching memory device applications.
Explanation:
Since this element has 50 electrons you know that it has 50 protons. The number of proton= the atomic number. Atomic number 50 is tin. The atomic symbol for tin is Sn and the weight is 120. So this is the tin 120 isotope
Reactants left products right
Answer:
First ionization of lithium:
.
Second ionization of lithium:
.
Explanation:
The ionization energy of an element is the energy required to remove the outermost electron from an atom or ion of the element in gaseous state. (Refer to your textbook for a more precise definition.) Some features of the equation:
- Start with a gaseous atom (for the first ionization energy only) or a gaseous ion. Write the gaseous state symbol
next to any atom or ion in the equation. - The product shall contain one gaseous ion and one electron. The charge on the ion shall be the same as the order of the ionization energy. For the second ionization energy, the ion shall carry a charge of +2.
- Charge shall balance on the two sides of the equation.
First Ionization Energy of Li:
- The products shall contain a gaseous ion with charge +1
as well as an electron
. - Charge shall balance on the two sides. There's no net charge on the product side. Neither shall there be a charge on the reactant side. The only reactant shall be a lithium atom which is both gaseous and neutral:
.
- Hence the equation:
.
Second Ionization Energy of Li:
- The product shall contain a gaseous ion with charge +2:
as well as an electron
. - Charge shall balance on the two sides. What's the net charge on the product side? That shall also be the charge on the reactant side. What will be the reactant?
- The equation for this process is
.