A 4.99 g sample of an unknown element contains 1.07 × 1023 atoms. Identify the unknown element.
Question
A 4.99 g sample of an unknown element contains 1.07 × 1023 atoms. Identify the unknown element.
Solution
To identify the unknown element, we need to find its atomic mass. We can do this by using Avogadro's number, which states that one mole of any substance contains 6.022 x 10^23 entities (atoms, in this case).
Step 1: Calculate the number of moles in the sample We know that the sample contains 1.07 x 10^23 atoms. To find the number of moles, we divide this number by Avogadro's number:
Number of moles = 1.07 x 10^23 atoms / 6.022 x 10^23 atoms/mole = 0.1778 moles
Step 2: Calculate the atomic mass We know that the sample weighs 4.99 g. To find the atomic mass, we divide this weight by the number of moles:
Atomic mass = 4.99 g / 0.1778 moles = 28.07 g/mole
Step 3: Identify the element The atomic mass we calculated is closest to that of silicon (Si), which has an atomic mass of approximately 28.09 g/mole. Therefore, the unknown element is likely silicon.
Similar Questions
How many atoms of 12C are there in a 3.50 gram sample of this particular isotope?Question 5Select one:a.1.72 x 1023b.1.76 x 1023c.2.07 x 1024d.2.11 x 1024e.8.01 x 1023
An unknown element was collected during a chemical reaction. The sample of the unknown element with a mass of 4.00 g was then allowed to react with excess oxygen, forming an oxide with a mass of 6.63 g. The oxide contains an equal amount (in mol) of both elements (the unknown element and oxygen). Identify the unknown element.
A sample of element X contains 69 % of 63X and 31 % of 65X.What is the relative atomic mass of X in this sample?A. 63.0B. 63.6C. 65.0D. 69.0
A certain sample of element Z contains 60% of 69Z and 40% of 71Z. What is the relative atomic mass ofelement Z in this sample?A. 69.2B. 69.8C. 70.0D. 70.2
If 6.02 × 1023 atoms of nitrogen have a mass of 14.0 g, what is the atomic mass of nitrogen?
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.