• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

a few quetsions (1 Viewer)

pqd123

Member
Joined
Aug 15, 2009
Messages
34
Location
sydney
Gender
Male
HSC
2010
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

Member
Joined
Jun 9, 2004
Messages
249
Gender
Undisclosed
HSC
N/A
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

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

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

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
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top