Guys heres a chance to earn many much points:

1. define valence electron and identify number of valence electrons in an element using periodic table
2. describe and identify properties of chemical bonding: ionic and covalent
3. identify the elements and calculate the number of atoms in a chemical formula
4. identify special properties of water including surface tension and specific heat (5.04)
5. explain how the bonds between water molecules affect its properties
6. compare acids and bases. be able to explain their properties and
give examples
7. know ph scale and explain hydronium and hydroxide concentration
8. explain how to use an acid-base indicator to determine ph

give correct answers or i will !

3. Identify the elements and calculate the number of atoms in a chemical formula

All the capital letter in a chemical formula are the elements and if they have a number next to it that indicates the amount of atoms in the chemical formula if there is no number then there is 1.

We breathe out CO2 when we exhale. The chemical formula for carbon dioxide shows that carbon dioxide contains atoms of carbon (C) and oxygen (O).

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

am i too late?

explanation: