Classify each of these statements as always true, sometimes true, or never true
1)___AT_____A mole of a pure substance contains 6.02 X 1023 atoms.
2)____ST____The representative particle of a compound is the molecule.
3)___NT_____A mole of CCl4 is composed of one atom of carbon and four atoms of chlorine.
4)____NT____ A mole of carbon atoms has a mass approximately three times as great as the mass of a mole of helium atoms.
1,2,3 are ok.
4 needs work.
The molar mass of He is about 4.
The molar mass of C is about 12. Look on the periodic chart to confirm this.
To classify each statement as always true, sometimes true, or never true:
1) A mole of a pure substance contains 6.02 x 10^23 atoms.
This statement is always true. It is a fundamental concept in chemistry known as Avogadro's number, which states that one mole of any substance contains 6.02 x 10^23 particles.
2) The representative particle of a compound is the molecule.
This statement is sometimes true. In many cases, especially for covalent compounds, the representative particle is indeed the molecule. However, in cases where the compound is composed of ions, such as sodium chloride (NaCl), the representative particle is not a molecule, but rather an ion.
3) A mole of CCl4 is composed of one atom of carbon and four atoms of chlorine.
This statement is never true. CCl4, also known as carbon tetrachloride, is a covalent compound that consists of one carbon atom and four chlorine atoms. Therefore, a mole of CCl4 contains one mole of carbon atoms and four moles of chlorine atoms.
4) A mole of carbon atoms has a mass approximately three times as great as the mass of a mole of helium atoms.
This statement needs correction. The molar mass of helium (He) is approximately 4 grams/mole. The molar mass of carbon (C) is approximately 12 grams/mole. Therefore, a mole of carbon atoms has a mass three times as great as the mass of a mole of helium atoms.
To summarize:
1) Always true
2) Sometimes true
3) Never true
4) Needs correction, a mole of carbon atoms has a mass approximately three times as great as the mass of a mole of helium atoms.