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Five moles of an unknown element have a mass of 35 g. What is the element?

User Dumoko
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Final answer:

The unknown element with a mass of 35 g for five moles is determined to have a molar mass of 7 g/mol, which is closest to the atomic mass of lithium (Li) on the periodic table.

Step-by-step explanation:

In this chemistry problem, we are given the mass of five moles of an unknown element and asked to identify it. Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). By knowing that five moles of the unknown element weigh 35 grams, we can calculate its molar mass as follows:

  • Molar mass of unknown element = Total mass / Number of moles
  • Molar mass of unknown element = 35 g / 5 moles
  • Molar mass of unknown element = 7 g/mol

Using the periodic table, we look for an element with a molar mass close to 7 g/mol, which corresponds to lithium (Li), with an atomic mass of approximately 6.94 g/mol. Hence, the unknown element is likely lithium.

User Gsinha
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