Chemistry Answers

A new sunscreen has been developed that is supposed to be more effective at preventing sunburn. 30 participants spray one arm with the new formula ,and spray the other arm with the leading formula. After 4 hours in the sun, their skin is evaluated for any redness

the production of 2.0 moles of HCl would require 70. grams of Cl₂ and —

How many moles are in 50.4g of CaBr2

if 100cm of hydrogen is sparked with 40cm3 of oxygen to produce H2O at s.t.p, calculate the volume of the gas that is in excess

Assignment 1: Application of static fluid principles

10.A reservoir of carbon tetrachloride has a mass of 500Kg

and a volume of 0.315 m^3. Find:

a) Weight of carbon tetrachloride

b) Mass density of carbon tetrachloride

c) Specific weight of carbon tetrachloride

d) Specific gravity of carbon tetrachloride

 Use the localized electron model to describe the bonding in hydrogen cyanide and 

    Phosgene (COCl2).

For which cation does fluoride ion have no masking effect? Al_Mo_Be_Fe

A reaction has a rate constant, k = 1.29 s^-1. What is the half-life (seconds) when the initial concentration is 0.784 M?

Direction: Solve the following problems. Attach your solutions.

1. Calculate the standard enthalpy ∆H°, for the following reaction:

2CH3OH (l) + 3O2 (g) ---> 2CO2 (g) + 2H2) (g)

Given: CH3OH (l) ∆Hf° = - 238.7 kJ

CO2 (g) ∆Hf° = - 393.5 kJ

H2O (l) ∆Hf° = - 285.8 kJ

Essay.

Water, compared to other substances, has one of the highest specific heat values. What is the advantage of this fact for the human body?

1. Calculate the enthalpy change for the following chemical reaction:

CS₂(1) + 3O₂(g) ---> CO₂(g) + 2SO₂(g)

1.C(s) + O₂(g) ---> CO₂(g) ∆H° = - 393.5 kJ

2.S(s) + O₂(g) ---> SO₂(g) ∆H° = - 296.8 kJ

4.C(s) + 2S(s) ---> CS₂(1) ∆H° = + 87.9 kJ