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kumpel [21]
3 years ago
9

What is the ROUNDED atomic number for this elements?

Chemistry
1 answer:
denis-greek [22]3 years ago
8 0
Sodium/Atomic number

11

Gold/Atomic number

79
Potassium/Atomic number

19

Silicon/Atomic number

14




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2
son4ous [18]

Answer: The molar enthalpy change is 73.04 kJ/mol

Explanation:

HCl+NaOH\rightarrow NaCl+H_2O

moles of HCl= molarity\times {\text {vol in L}}=0.415mol/L\times 0.1=0.0415mol

As NaOH is in excess 0.0415 moles of HCl reacts with 0.0415 moles of NaOH.

volume of water = 100.0 ml + 50.0 ml = 150.0 ml

density of water = 1.0 g/ml

mass of water = volume \times density=150.0ml\times 1.0g/ml=150.0g

q=m\times c\times \Delta T

q = heat released

m = mass  = 150.0 g

c = specific heat = 4.184J/g^0C

\Delta T = change in temperature = 4.83^0C

q=150.0\times 4.184\times 4.83

q=3031.3J

Thus 0.0415 mol of HCl produces heat = 3031.3 J

1 mol of HCL produces heat = \frac{3031.3}{0.0415}\times 1=73043.3J=73.04kJ

Thus molar enthalpy change is 73.04 kJ/mol

8 0
3 years ago
A sample of nitrogen gas has the temperature drop from 250.°c to 150.°c at constant pressure. what is the final volume if the in
Leviafan [203]
Charles law gives the relationship between temperature of gas and volume of gas.
It states that for a fixed amount of gas, temperature is directly proportional to volume of gas.
V / T = k
where   V- volume , T - temperature and k - constant 
\frac{V1}{T1} =  \frac{V2}{T2}
parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation.
T1 = 250 °C + 273 = 523 K
T2 = 150 °C + 273 = 423 K
Substituting the values in the equation,

\frac{310 mL}{523 K} =  \frac{V}{423K}
V = 251 mL
the new volume is 251 mL 
6 0
3 years ago
The image shows a molecular model of a compound using balls and sticks. Each ball is an atom and each stick is a bond. If you we
Zielflug [23.3K]
Hi , the answers must be part B
3 0
3 years ago
Read 2 more answers
For the reaction C2H4(g) + H2O(g) --> CH3CH2OH(g)
Dominik [7]

Answer : The value of equilibrium constant for this reaction at 262.0 K is 3.35\times 10^{2}

Explanation :

As we know that,

\Delta G^o=\Delta H^o-T\Delta S^o

where,

\Delta G^o = standard Gibbs free energy  = ?

\Delta H^o = standard enthalpy = -45.6 kJ = -45600 J

\Delta S^o = standard entropy = -125.7 J/K

T = temperature of reaction = 262.0 K

Now put all the given values in the above formula, we get:

\Delta G^o=(-45600J)-(262.0K\times -125.7J/K)

\Delta G^o=-12666.6J=-12.7kJ

The relation between the equilibrium constant and standard Gibbs free energy is:

\Delta G^o=-RT\times \ln k

where,

\Delta G^o = standard Gibbs free energy  = -12666.6 J

R = gas constant  = 8.314 J/K.mol

T = temperature  = 262.0 K

K = equilibrium constant = ?

Now put all the given values in the above formula, we get:

-12666.6J=-(8.314J/K.mol)\times (262.0K)\times \ln k

k=3.35\times 10^{2}

Therefore, the value of equilibrium constant for this reaction at 262.0 K is 3.35\times 10^{2}

3 0
4 years ago
A compound is composed of 13% carbon, 4.3% hydrogen, 30.4% nitrogen, and 52.2% oxygen. The mystery compound has a molar mass of
vredina [299]

Answer:

C₂H₈N₄O₆ is the molecular formula for the compound

Explanation:

Data from the problem:

13 g of C in 100 g of compound

4.3 g of H in 100 g of compound

30.4 g of N in 100 g of compound

52.2 g of O in 100 g of compound

Firstly we determine, the mass of each in 184 g of compound, which is 1 mol

(13 g / 100 g) . 184 g  = 24 g C

(4.3 g  / 100 g) . 184 g  = 7.91 g H ≅ 8 g H

(30.4 g / 100 g) . 184 g  = 56 g N

(52.2 g  / 100 g) . 184 g  = 96 g O

And now, we divide the mass by the molar mass of each to determine the moles:

24 g C / 12 g/mol = 2 mol C

8g H / 1 g/mol = 8 mol H

56 g N / 14 g/mol = 4 mol N

96 g O / 16 g/mol = 6 mol O

So the molecular formula of the compound is C₂H₈N₄O₆

8 0
3 years ago
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