Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
<u>C. 571.6 kJ</u>
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :
Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ
The coefficient for hydrogen in the balanced equation of solid molybdenum(iV) oxide with gaseous hydrogen is 2
Explanation
Coefficient is defined to as a number in front of a chemical formula in a balanced chemical equation.
The reaction of molybdenum (iv) oxide with gaseous hydrogen is as below,
MoO2 + 2 H2→ Mo +2 H2O
From balanced equation above the coefficient for H2 is 2 since the number in front of H2 is 2
It has 78 neutrons in a cesium
Answer:
1.The Aluminum block
2.its surroundings absorb energy from it.
Explanation:
In this question it is important to remember that density of an object is the mass of that object divided by its volume.
The expression applied here is density=mass/volume
Given that the mass is constant,lets say mass= m=1g
and density of aluminum=2.7g/cm³ and that of iron is 7.8 g/cm³ then volume=?
Volume=mass/density
Volume of aluminum= 1/2.7 =0.3704 cm³
Volume of iron = 1/7.8 =0.1282 cm³
Here we see volume of Aluminum block is the largest.
2.As water in an ice cube tray freezes, its surroundings absorb energy from it.When the water freezes, latent heat of freezing is given out to the surrounding.When water is freezing, it stays at a constant temperature of 0°C, the heat energy released ensures that there is no cooling past 0 °C.
