Answer:
2) 0.4 mol
Explanation:
Step 1: Given data
- Volume of the solution (V): 500 mL
- Molar concentration of the solution (M): 0.8 M = 0.8 mol/L
Step 2: Convert "V" to L
We will use the conversion factor 1 L = 1000 mL.
500 mL × 1 L/1000 mL = 0.500 L
Step 3: Calculate the moles of KBr (solute)
The molarity is the quotient between the moles of solute (n) and the liters of solution.
M = n/V
n = M × V
n = 0.8 mol/L × 0.500 L = 0.4 mol
<span>One mole of a substance contains Avogadro's number of atoms/molecules/the like. This would mean that all of the items described would have approximately 6.022 * 10^23 atoms, even though their masses would differ. This would be due to the molar mass of each substance being different because of the constituent elements in the substance.</span>
Since the density of water is 1 g /mL, hence there is 100
g of H2O. So total mass is:
m = 100 g + 5 g = 105 g
=> The heat of reaction can be calculated using the
formula:
δhrxn = m C ΔT
where m is mass, C is heap capacity and ΔT is change in
temperature = negative since there is a decrease
δhrxn = 105 g * 4.18 J/g°C * (-2.30°C)
δhrxn = -1,009.47 J
=> However this is still in units of J, so calculate
the number of moles of NaCl.
moles NaCl = 5 g / (58.44 g / mol)
moles NaCl = 0.0856 mol
=> So the heat of reaction per mole is:
δhrxn = -1,009.47 J / 0.0856 mol
δhrxn = -11,798.69 J/mol = -11.8 kJ/mol
B - two hydrogen atoms and one oxygen atom
Energy were released from the walnut, q = 1,673.6 J
<h3>Equation :</h3>
To find the energy using formula,
q = mcΔt
where,
q is charge
m is mass
c is specific heat of water
Δt is change in temperature
So, given
t₁ = 50°C
t₂ = 60°C
m = 40g
c = 4.184 J/g
Now putting the values known,
We get,
q = mc(t₂ - t₁)
q = 40g x 4.184 J/g x (60 - 50)
q = 167.36 J x 10
q = 1,673.6 J
<h3>What is heat energy?</h3>
Heat is the thermal energy that is transferred when two systems with different surface temperatures come into contact. Heat is denoted by the letters q or Q and is measured in Joules.
To know more about specific heat :
brainly.com/question/11297584
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