Pete complete a 40 question test, and got 75% of the questions right. How many questions did he get wrong?
Write 75% as a decimal. 75/100 x 40 questions = 30 correct questions. How many did Peter get incorrect? 40 total questions - 30 correct questions = 10 incorrect answers.
Two moles of aluminum reacts with excess chlorine to form two moles of aluminum chloride. If 80 grams of aluminum is reacted with excess chlorine, how many moles of aluminum chloride will be formed? 2Al + 3Cl2 ---> 2AlCl3
First, calculate how many moles of aluminum there are in 80g. 80 grams of aluminum/27g aluminum = 2.96 moles of aluminum. Divide by 27g of Al as there are 27g of aluminum per mole. From the balanced equation above, the stoichiometry of Al in reactants and AlCl3 in the product are equal. There are 2 moles of Al and 2 moles of AlCl3. Therefore, 2.96 moles of aluminum will react to form 2.96 moles of aluminum chloride.
If an atom has 15 electrons, how many orbitals will it have?
An atom with 15 electrons will have 3 orbitals. The first orbital can contain a maximum of two electrons. The second and third orbitals can contain a maximum of eight orbitals each. So, 2 electrons in the first orbital, plus 8 electrons in the second orbital gives a total of 10 electrons. The atom has 15 electrons, so there are 5 atoms present in the third orbital,