Question

Question 15 (2 points) ✓ Saved The molecular model for Propylene glycol is shown below. What is its empirical formula? carbon hydrogen O oxygen O A) C₂H40 B OB) C3H8O2 C) CH40 D) C3H40

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Answer 1

1. By counting the number of atoms of each element in the molecular model, we get the molecular formula. An empirical formula is the simplest ratio of all the elements in the compound. When the common factor is taken out of the molecular formula, we get the empirical formula.

The molecular formula of the given model is: C₃H₈O₂

3, 8, and 2 do not have any common factor. So here, empirical formula = molecular formula.

Thus, empirical formula = C₃H₈O₂ (B)

2. Sulfate ion has a charge of 2-. As XSO₄ is a neutral compound, that means X has a charge of 2+ (X²⁺). Now, by criss-cross method, the formula with the chloride would be XCl₂ (D).

х CI XCI, Charge: 2+ 1 -

3. The ion has 25 electrons and a charge of +3. This means the ion has lost 3 electrons.

So, number of electrons in the neutral atom = 25 + 3 = 28

For a neutral atom, atomic number = number of protons = number of electrons = 28

The atom with atomic number 28 is nickel (Ni). Thus, the given ion is an ion of Ni (D).

4.

1000 g 7.75 g/cc Given, Density of the rod (D) = 7.75 g/cc Diameter of the rod (d) = 2.54 cm Mass to be cut (M) = 1000 g So, Mass M 1000 g Density D = 7.75 g/cc = V= Volume V V 129.03 cc d? A rod is cylindrical object and volume of cylinder = ar?h=14h 4 Fomr the above two equation, we get d2 2.542 129.03 (3.14) -)h = 129.03 4 4 129.03 x 4 = 25.48 cm 3.14 x 2.54 x 2.54 25.48 cm would be cut out from the rod. -h h =

5.

Density Mass Volume

All the metals given have equal volumes. So, the mass would directly depend on the density. The metal having the highest density will have the highest mass.

Out of the given metals, platinum has the highest density (21.3 g/mL). So, it has the highest mass.

Thus, platinum (21.3 g/mL) (A) will have the highest mass.

6. In the given diagram, 6 atoms of A combine with 4 atoms of B to form 4 atoms of C and 2 atoms of D. This can be represented in the form of a chemical equation as

6A + 4B --> 4C + 2D

3 1 5 0 3 в A A 1 с) 1р) 30) 2p) 40) 24 B В 24 2 © 64

Or, taking the common factor (2) out, 3A + 2B --> 2C + D.

So, (A) is the correct answer.