Answer:
A. 2NO + O2 -> 2NO2
B. 4Co + 3O2 -> 2Co2O3
C. 2Al + 3Cl2 -> Al2Cl6
D. 2C2H6 + 7O2 -> 4CO2 + 6H2O
E. TiCl4 + 4Na -> Ti + 4NaCl
The given example is a chemical reaction.
The contents (separated as reactants and products) :

The written reaction is :

<em>I hope it helped you solve the problem.</em>
<em>Good luck on your studies!</em>
Answer:
<h3>25.0 grams is the mass of the steel bar.</h3>
Explanation:
Heat gained by steel bar will be equal to heat lost by the water

Mass of steel=
Specific heat capacity of steel =
Initial temperature of the steel = 
Final temperature of the steel = 

Mass of water= 
Specific heat capacity of water=
Initial temperature of the water = 
Final temperature of water = 

On substituting all values:

<h3>25.0 grams is the mass of the steel bar.</h3>
Answer:
2.25g of NaF are needed to prepare the buffer of pH = 3.2
Explanation:
The mixture of a weak acid (HF) with its conjugate base (NaF), produce a buffer. To find the pH of a buffer we must use H-H equation:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH of the buffer that you want = 3.2, pKa is the pKa of HF = 3.17, and [] could be taken as the moles of A-, the conjugate base (NaF) and the weak acid, HA, (HF). </em>
The moles of HF are:
500mL = 0.500L * (0.100mol/L) = 0.0500 moles HF
Replacing:
3.2 = 3.17 + log [A-] / [0.0500moles]
0.03 = log [A-] / [0.0500moles]
1.017152 = [A-] / [0.0500moles]
[A-] = 0.0500mol * 1.017152
[A-] = 0.0536 moles NaF
The mass could be obtained using the molar mass of NaF (41.99g/mol):
0.0536 moles NaF * (41.99g/mol) =
<h3>2.25g of NaF are needed to prepare the buffer of pH = 3.2</h3>