Answer:
Explanation:
q= mc theta
where,
Q = heat gained
m = mass of the substance = 670g
c = heat capacity of water= 4.1 J/g°C
theta =Change in temperature=(
66-25.7)
Now put all the given values in the above formula, we get the amount of heat needed.
q= mctheta
q=670*4.1*(66-25.7)
=670*4.1*40.3
=110704.1
Percentage error is the relative error your measured value is from the true or accepted value. The formula for percentage error is written below:
Percentage error = |True Value - Measured Value|/True Value * 100
Percentage error = |0.75 g/mL - 0.78 g/mL|/0.75 g/mL * 100
Percentage error = 4%
A volumetric flask is used to contain a predetermined volume of substance and only measures that volume, for example 250 ml.
Conical flasks can be used to measure the volume of substances but the accuracy they provide is usually up to 10ml. Conical flasks are used in titrations, reactions where the liquid may boil, and reactions which involve stirring.
Pippettes are of two types, volumetric and graduated. Pippettes are used where high accuracy is required and volumetric pippettes come in as little as 1 ml. Pippettes are usually used in titrations.
Graduated cylinders come in a wide variety of sizes and their accuracy can be down to as much as 1 ml. They are used to contain liquids.
Answer:
203 grams
Explanation:
<em>It is known that 1.0 mole of a compound contains Avogadro's number of molecules (6.022 x 10²³).
</em>
<em><u>Using cross multiplication:</u></em>
1.0 mol contains → 6.022 x 10²³ molecules.
??? mol contains → 7.2 x 10²⁴ molecules.
∴ The no. of moles of (6.3 x 10²⁴ molecules) of NH₃ = (1.0 mol)(7.2 x 10²⁴ molecules)/(6.022 x 10²³ molecules) = 11.96 mol.
<em>∴ The no. of grams of NH₃ present = no. of moles x molar mass </em>= (11.96 mol)(17.0 g/mol) = <em>203.3 g ≅ 203.0 g.</em>
Answer:
Both reaction A and reaction B are non spontaneous.
Explanation:
For a spontaneous reaction, change in gibbs free energy (
) should be negative.
We know, 
, where T is temperature in Kelvin scale.
Reaction A: 
As is positive therefore the reaction is non-spontaneous.
If at a temperature T K , the reaction is spontaneous then-
or, 
or, 
or, 
So at a temperature greater than 350 K, the reaction is spontaneous.
Reaction B: 
As is positive therefore the reaction is non-spontaneous.
If at a temperature T K , the reaction is spontaneous then-
or,
or, 
or, 
So at a temperature greater than -16 K, the reaction is spontaneous.
