The density of a material is the mass of the material per unit volume. Here the weight of the same metal is 44.40g, 40.58g and 38.35g having volume 4.8 mL, 4.7 mL and 4.2 mL respectively. Thus the density of the metal as per the given data are, = 9.25g/mL, = 8.634g/mL and = 9.130g/mL respectively.
The equation of the standard deviation is √{∑(x - )÷N}
Now the mean of the density is {(9.25 + 8.634 + 9.130)/3} = 9.004 g/mL.
The difference of the density of the 1st metal sample (9.25-9.004) = 0.246 g/mL. Squaring the value = 0.060.
The difference of the density of the 2nd metal sample (9.004-8.634) =0.37 g/mL. Squaring the value = 0.136.
The difference of the density of the 3rd metal sample (9.130-9.004) = 0.126 g/mL. Squaring the value 0.015.
The total value of the squared digits = (0.060 + 0.136 + 0.015) = 0.211. By dividing the digit by 3 we get, 0.070. The standard deviation will be . Thus the standard deviation of the density value is 0.265g/mL.
<h2>Answer:</h2>
<em>8.67kJ/mol</em>
<h2>Explanations</h2>
The formula for calculating the amount of heat absorbed by the water is given as:
Determine the moles of KI
Since heat is lost, hence the enthalpy change of the solution will be negative that is:
Determine the enthalpy of solution in kJ•mol-1
Hence the enthalpy of solution in kJ•mol-1 for KI is 8.67kJ/mol
One mole of oxygen gas, which has the formula O2, has a mass of 32 g and contains 6.02 X 1023 molecules of oxygen but 12.04 X 1023 (2 X 6.02 X 1023) atoms, because each molecule of oxygen contains two oxygen atoms.
To write a balanced chemical equation for the given redox reaction, we need to know the half reactions of the substances involved. Redox reaction means oxidation-reduction reaction. Oxidation is when one loses electrons making it more positive while reduction is gaining electrons which makes it more negative. Iron here is being oxidized and will have the half reaction:
<span>Fe2+(aq) ---> Fe3+(aq) + e+
</span>
<span> S2O2−6 is being reduced in the process and will have a half reaction of:
</span>S2O2-6 + 4H+ + 2e- ----> <span>2H2SO3
</span>
Adding the two half reactions would yield to the balanced chemical equation. We do as follows:
2 (Fe2+ ---> Fe3+ + e+)
S2O2-6 + 4H+ + 2e- ----> 2H2SO3
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2Fe2+ + S2O2-6 + 4H+ ----> 2Fe3+ + 2H2SO3 ( balanced oxidation - reduction reaction )