<h3><u>Answer;</u></h3>
Molarity = 0.25 M
<h3><u>Explanation;</u></h3>
Molarity is given by moles/Liter.
First we find moles:
Number of moles = Mass /molar mass
= (10.7g NH4Cl)/(53.5g/mol NH4Cl)
= 0.200 moles NH4Cl
Then we convert to liters:
= (800mL)*(1L/1000mL) = 0.800L
Therefore; molarity = 0.2moles/0.8L
= 0.25M
Answer:
False
Explanation:
Lead sulfate is insoluble in water and sinks in water
(sorry if it's wrong)
It will dissolve fastest in a cup of hot water.
Heat = mass * heat capacity of water * change in temperature
mass = 5.25 g
heat capacity of water = 4.186 joule/gram °C
Change in temperature = 62.8°C - 5.3°C = 57.5 °C
Plug in the values
heat = 5.25 g * 4.186 joule/gram °C * 57.5 °C = 1263.6 J
Rounded to two three significant figures, it is 1260 J of energy needed.
In terms of calories, the heat capacity of water is 1 calorie/gram °C. So do the plugging in all over again.
mass = 5.25 g
heat capacity of water = 1 calorie/gram °C
Change in temperature = 62.8°C - 5.3°C = 57.5 °C
heat = 5.25 g * 1 calorie/gram °C * 57.5 °C = 301.9 calories
Rounded to 3 significant figures, it is 302 calories
Q=SM∆T=4.18*5.25*(62.8-4.3)=1280 J
1280 J * (1 cal/4.18 J) = 307 cal