How much energy (kJ) is required to convert a 25.0 g ice cube at -15.°C to water vapor at 250°C?

Determine the boiling point of a solution if the molality of a non-ionizing and non-volatile solute was 0.592 mol/kg. (The boiling point elevation constant for water is 0.51oC/m.)

Determine the freezing point of a solution is the molality of a non-ionizing solute was 0.467 mol/kg. (The freezing point depression constant for water is 1.86 ^oC/m.)

What is the mole fraction of Compound A in a mixture containing 2.56 g of compound A (MM = 175.4 g/mol) and 5.7 g of Compound B(MM = 216.1g/mol)?

What is the molality of Compound A in a solution containing 8.98 g of Compound A(MM = 110.4 g/mol) and 98.86 g of water (MM = 18.0 g/mol)?

Determine the molarity when 21.9 g of Compound A (MM = 148.8 g/mol) are dissolved into enough water to make a solution of 684 mL. (Do not include units.)

What is the percent by mass of copper in an alloy containing 3.35 g of copper and 7.47 g of nickel?

What is the mass of a compound needed to make a 249.0 mL of a solution with a molarity of 4.67 M? The molar mass of the compound is 156.9 g/mol. (Do not include units)

If an object is at point x,y,z (Cartesian coordinates) and its symmetry mate is related by a 21 screw axis, what is the location in Cartesian coordinates for the symmetry mate?

Nitric acid is often manufactured from the atmospheric gases nitrogen and oxygen, and hydrogen prepared by reforming natural gas, in a two-step process. In the first step, nitrogen and hydrogen react to form ammonia: N 2 ( g ) + 3 H 2 ( g ) → 2 NH 3 ( g )

In the second step, ammonia and oxygen react to form nitric acid HNO 3 and water: NH 3 ( g ) + 2 O 2 ( g ) → HNO 3 ( g ) + H 2 O ( g )

Suppose the yield of the first step is 86. % and the yield of the second step is 74. % . Calculate the mass of hydrogen required to make 8.0 kg of nitric acid. Be sure your answer has a unit symbol, if needed, and is rounded to 2 significant digits.

Give at least two possibilities for why enzymes could be partially protected from heat denaturation through high substrate concentrations.

PLEASE HELP!

Why is it advantageous to use one reagent in excess when you do a reaction?

-Ideally what kind of property must the reagent used in excess have in comparison to the properties of the product in order to be used in excess?

Consider separate 1.0 L samples of the following gases at STP: Cl₂, C₂H₆, and Xe.
Which of the following statements are true regarding these gas samples?


TrueFalse The C₂H₆ gas sample has the most molecules of gas present.

TrueFalse The C₂H₆ gas sample has the smallest average kinetic energy.

TrueFalse The mass of the gas in each container is different.

TrueFalse The C₂H₆ gas sample has the lowest density.

TrueFalse Each Xe gas particle collision with the container wall is more forceful as compared to each C₂H₆ and Cl₂ collision.

TrueFalse The C₂H₆ gas molecules collide with the container walls most frequently.
i put false, false, true, true, false, false but its wrong

The reversible chemical reaction

A+B⇌C+D

has the following equilibrium constant:

Kc=[C][D][A][B]=4.7

Part A

Initially, only A and B are present, each at 2.00 M . What is the final concentration of A once equilibrium is reached?

Express your answer to two significant figures and include the appropriate units.

Part B

What is the final concentration of D at equilibrium if the initial concentrations are [A] = 1.00 M and [B] = 2.00 M ?

Express your answer to two significant figures and include the appropriate units

A beaker with 175 mL of an acetic acid buffer with a pH of 5.000 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100 M. A student adds 8.20 mL of a 0.400 MHCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.740.

A sample of gas occupies 300 ml at STP. Under what pressure would this sample occupy a volume of 150 ml at a temperature of 546 ̊C?

Calculate the pressure exerted by 60.0 g C2H6 (ethane) in a 30.0-L vessel at 27 ̊C.

When nickel is heated in carbon monoxide, a gaseous product is formed that has a density of 6.57 g/L at 750 torr and 40 ̊C. The compound is analyzed to show 34.30% Ni, 28.1% C and 37.53% O. What is the molecular formula of the compound?

If 2.0 liters of N2 at 2.0 atm and 2.0 liters of H2 at 1.0 atm are put in a 4.0-liter vessel, what is the final pressure, temperature being constant?

Two gases, Ar and He, are contained in vessel. The mole fraction of He is 0.35 with a partial pressure of 1.15 atm. What is the partial pressure of Ar?

Given the reaction below, how many grams of iron are needed to produce 100 liter of hydrogen gas at STP?

3Fe(s) + 4H2O(l) → Fe3O4 (s) +4H2 (g)

What volume of oxygen at 18 ̊C and 750 torr can be obtained from the thermal decomposition of 100-g KClO3?

2KClO3 (s) → 2KCl(s) +3O2 (g)

A student collects 2.63 L of O2 over water at 29 ̊C and 769 torr by thermal decomposition of potassium chlorate. a) How many grams of oxygen are in the sample? b) How many grams of KClO3 decomposed to produce the oxygen?

2KClO3 (s) → 2KCl (s)+ 3O2 (g)

A 25.00 mL sample of 0.280 M NaOH analyte was titrated with 0.750 M HBr at 25 °C. Calculate the initial pH before any titrant was added. Calculate the pH after the 5.00ml titrant was added.

Metallic magnesium can be made by the electrolysis of molten MgCl2.

(a) What mass of Mg is formed by passing a current of 6.79 A through molten MgCl2 for 1.80 days? The unbalanced chemical reaction representing this electrolysis is shown below. MgCl2 Mg + Cl2 g of Mg is formed by this electrolysis.

(b) How many minutes are needed to plate out 11.00 g of Mg from molten MgCl2 using 5.46 A current? minutes are needed.

Consider the following reaction:
HC2H3O2(aq)+H2O(l)?H3O+(aq)+C2H3O?2(aq)
Kc=1.8