I have 5 questions in chemistry :
1-How many benzene molecules are present in 7.0 mL of benzene at 25 oC?
2-How many electrons are in two moles of potassium, K?
3-What mass of sodium sulfate is needed to prepare 270 mL of a solution having a sodium ion concentration of 0.32 M?
4-Liquid heptane burns in oxygen gas to yield carbon dioxide and water. What mass of carbon dioxide is produced when 23.0 cm3 of heptane burns completely?
5-When hexane is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 81%. What mass of carbon dioxide will be produced in this engine when 10.0 g of hexane is burned with 20.0 g of oxygen gas?
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1. An experimental determination of the molecular mass reveals that a molecule of benzene contains six carbon atoms and six hydrogen atoms, so the molecular formula for benzene is C6H6 .
2.1 mole of electrons contains the Avogadro constant, L, electrons - that is 6.02 x 1023 electrons.
3.To obtain 1 M solution, it is simply to weigh 78.0452 g, dissolve them in sufficient amount of solvent (water) and add solvent (water) up to 1 liter. If small quantities are preferred; dissolve 7.80452 g Na2S in sufficient amount of solvent (water) and add solvent (water) up to 100 mL.
4.313.6 L of carbon dioxide will be produced from the complete combustion of 2.00 moles of heptane.
5.While diesel fuel combustion engines produce lower levels of carbon monoxide than gasoline engines, these emissions can still generate lethal amounts of carbon monoxide given a sufficient amount of time in an enclosed space. Carbon monoxide makes up anywhere from 2% to 12% of diesel exhaust gases.