[chemistrie]

Hope someone can answer the following few questions:

1. Suppose a hard substance has a very high melting point and doen't conduct electricity in both solid state and molten state, then which of the following is the possible structure of it?

a. Giant structure of  atoms of a non-metal.
b. Giant structure of ions
c. Structure of separate, small and identical groups of atoms
d. structure of separate and free atoms

2. The condensation of noble gases at low temperatures to form liquids is due to:

a. Formation of covalent bond
b. The presence of weak van der Waal's force
c. the ionic character of covalent bonds
d. the repulsion of molecules

3. If 5g of magnesium reacts with 3.2g oxygen and magnesium oxide is formed, then which substance is the limiting agent?

4. What is the balanced chemical equation for rust reacts with dilute sulphuric acid?

[Donaldson Tan]

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[AWK]

1. http://www.chm.davidson.edu/ChemistryApplets/Crystals/NetworkSolids.html

2.http://www.newton.dep.anl.gov/askasci/chem99/chem99564.htm

3. write down the balanced equation . and think

4. What is rust - a difinite metal oxide. Write down the neutralization reaction.

[chemistrie]

For questions3, from the chemical equation, I noticed that 2moles of magnesium reacts with 1 mole of oxygen, when I divide the number of mole of magnesium by 2,Mg is the limiting agent. But if I didn't do that, oxygen seemed to be the limiting reactant in the reaction, so which one is right?

For question 4, I knew that the chemical formula of rust is Fe2O3 but I could not balance the equation, can someone help me?

[Mitch]

4.) You have Fe(0) going to Fe(III) try to figure it out.

[AWK]

3.
2Mg + O2 = 2MgO
two moles or 48 grams Mg reacts with 1 mole or 32 grams of oxygen,
so 3.2 g of oxygen shoould react with 4.8 g of Mg. We have more mangesium. Them oxygen is  the limiting reagent.

4.
Fe2O3 + 3H2SO4 = Fe2(SO4)3 + 3H2O