a few quetsions

[pqd123]

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i have a few questions which we havent covered in class yet and i dont have my textbook with me atm

1. carbon-12 compared to the isotope carbon 14 is:
a) stable because of the p : e ratio
b) unstable because it has too many protons
c) stable due to the ratio of the p : n
d) stable because it lies outside the region of stability for the p :n ratio

2. A radioactive atom of Group 5 element emits one beta particle. The decay product will be an atom of an element in group:
a) 3
b) 4
c) 5
d) 6

3. A substance that could not be formed when ethanol is burned in air is:
a) H
b) C
c) water
d) CO

4. To find the molar heat of reation for:
NaOH (aq) + HCl (aq) --> NaCl (aq) + H2O (l)
a student mixes 50mL of 0.2 mol/L NaOH and excess hydrochloric acid solutions in a polystyrene cup. He makes these measurements

Total mass of reaction : 100g
Temp of each solution before mixing : 16
highest temp of reaction mixture after mixing : 33

Assume the specific heat capacity of the reaction mixture is the same as water


1. im not sure because i thought that carbon-14 was unstable but i know that carbon 14 has a mass number of 14 so the ratio of p:n is less so it cant have too many protons and the rest say that its stable so im not sure

2. From my memory of prelim physics a beta paricle is a helium nucleus, so im thinking group 3...

3. no idea

4. is it H=-mCT ??? or is that just for molar heat of solution not reaction. not sure where the concentration comes in

[brenton1987]

Originally Posted by pqd123

1. carbon-12 compared to the isotope carbon 14 is:
a) stable because of the p : e ratio
b) unstable because it has too many protons
c) stable due to the ratio of the p : n
d) stable because it lies outside the region of stability for the p :n ratio

C

Originally Posted by pqd123

2. A radioactive atom of Group 5 element emits one beta particle. The decay product will be an atom of an element in group:
a) 3
b) 4
c) 5
d) 6

D

Originally Posted by pqd123

3. A substance that could not be formed when ethanol is burned in air is:
a) H
b) C
c) water
d) CO

A

Originally Posted by pqd123

4. To find the molar heat of reation for:
NaOH (aq) + HCl (aq) --> NaCl (aq) + H2O (l)
a student mixes 50mL of 0.2 mol/L NaOH and excess hydrochloric acid solutions in a polystyrene cup. He makes these measurements

Total mass of reaction : 100g
Temp of each solution before mixing : 16
highest temp of reaction mixture after mixing : 33

Assume the specific heat capacity of the reaction mixture is the same as water

H = m * C * dT
H = 100 * 4.18 * 17
H = 7106 kJ^.mol^-1