# Chemistry

Hydrazine, N2H4, is a colorless liquid used in rocket fuel. What is the enthalpy change for the process in which hydranzine is formed from its elements?

N2(g) + H2(g) => N2H4(l)

Use the following reactions and enthalpy changes:

N2H4 + O2 => 2H2O DeltaH = -622.2KJ
H2 + 1/2O2 => H2O DeltaH = -285.5KJ

So how would you do this?

1. 👍
2. 👎
3. 👁
1. Your first reaction is not quite complete:

N2H2 + O2 >> N2 + 2H2O deltaH=-622.2kJ/mol

H2+ 1/2 O2>>H2O deltaH=-285.5KJ

Well, if we double the second reaction, and subtract that from the first reaction

N2H2 -2H2 >> N2 deltaH=-622.2+2(285.5)
or
reversing the reaction...
N2+H2>>N2N2 deltaH= - above. So, the heat of formation is a +value, an endothermic process.

1. 👍
2. 👎
👤
bobpursley

## Similar Questions

1. ### physics

A 15.0-kg test rocket is fired vertically from Cape Canaveral. Its fuel gives it a kinetic energy of 1961 J by the time the rocket motor burns all the fuel. What additional height will the rocket rise? m - how do you organize

2. ### chemistry

A fuel mixture used in the early days of rocketry is composed of two liquids, hydrazine (N2H4) and dinitrogen tetraoxide (N2O4), which ignite on contact to form nitrogen gas and water vapor. 2 N2H4 + N2O4 --> 3 N2 + 6 H2O If 1.50

3. ### Chemistry

Hydrazine has the formula N2H4 and is used as a rocket fuel (e.g. for the Apollo moon rockets). It burns in the following reaction for which the enthalpy change is -583 kJ/mol. N2H4(g) + O2(g) → N2(g) + 2 H2O(g) Calculate the

4. ### chemistry

A 1.000 gram sample of the rocket fuel hydrazine (N2H4) is burned in a bomb calorimeter. The temperature rises from 24.62°C to 28.16°C. The heat capacity of the calorimeter (including the water) is 5860 J/°C. Calculate the

1. ### physics

A rocket engine uses fuel and oxidizer in a reaction that produces gas particles having a velocity of 1380 ms-1. The desired thrust is to be 195000 N. 1-What must be the fuel/oxidizer consumption rate (in kg s-1)? 2-f the initial

2. ### Chemistry

You wish to know the enthalpy change for the formation of liquid PCl3 from the elements shown below. P4(s) + 6 Cl2(g)--> 4 PCl3(l) ΔH°f = ? The enthalpy change for the formation of PCl5 from the elements can be determined

3. ### Enthalpy of Formation

N2H4(g) + H2(g)--> 2 NH3(g) H1 = –1876kJ 3 H2(g) + N2(g)--> 2 NH3(g) H2 = –922 kJ The H.f for the formation of hydrazine: 2 H2(g) + N2(g)--> N2H4(g) will be______kj/mol I am very confused here. I thought I would just add H1

4. ### AP Chemistry

Write the expression of for the base dissociation constant for hydrazine, N2H4, a weak base. Hydrazine reacts with water to form the N2H5+ ion.

1. ### Chemistry (PLZ HELP)

Hydrazine, N2H4(aq), is used in the preparation of polymers, pharmaceuticals and rocket fuel. Hydrazine has alkaline properties similar to ammonia and will act as a weak base. Given that a 100 mL sample of 0.10 mol/L hydrazine

2. ### physic

A sounding rocket, launched vertically upward with an initial speed of 79.0 m/s, accelerates away from the launch pad at 5.70 m/s2. The rocket exhausts its fuel, and its engine shuts down at an altitude of 1.15 km, after which it