Mrs. Stark weighs 70kg. How much Potential Energy does she have if she stands on the roof of an 80m tall building?

Elena-2011 [213]

Moles= mass\ relative formula mass(Ar)
moles of zinc= 7.9/30= 0.263
so we have 0.263 moles of zinc, and you need twice the amount of chlorine so therefore 0.526moles of chlorine= 0.526x 17=8.942g of chlorine
i cba to work the rest out but the most reasonable answer is 0.24 mol however if you need to use working outs, use the formula i provided earlier

8 0

2 years ago

20 mL of an approximately 10% aqueous solution of ethylamine, CH3CH2NH2, is titrated with 0.3000 M aqueous HCl. Which indicator

Eduardwww [97]

Answer:

Therefore, The indicator that is best fit for the given titration is Bromocresol Green Color change from pH between 4.0 to 5.6

Bromocresol green, color change from pH = 4.0 to 5.6

Explanation:

The equation for the reaction is :

$C_2H_5NH_2_(_a_q_) + H^+_(_a_q_) --- C_2H_5NH_{3(aq)}^+$

concentration of $C_2H_5NH_{2(aq)$ = 10%

10 g of $C_2H_5NH_{2(aq)$ in 100 ml solution

molar mass = 45.08 g/mol

number of moles = 10 / 45.08

= 0.222 mol

Molarity of $C_2H_5NH_2(aq) = 0.222 \times \frac{1000}{100}mL$

= 2.22 M

number of moles of $C_2H_5NH_{2(aq)$ in 20 mL can be determined as:

$= 20 mL \times 2.22 M= 44*10^{-3} mole$

Concentration of $C_2H_5NH_2(aq) = \frac{44*10^{-3}*1000}{20}$

= 2.22 M

Similarly, The pKa Value of $C_2H_5NH_{2(aq)$ is given as 10.75

pKb value will be: 14 - pKa

= 14 - 10.75

= 3.25

the pH value at equivalence point is,

$pH= \frac{1}{2}pKa - \frac{1}{2}pKb-\frac{1}{2}log[C]$

$pH = \frac{14}{2}-\frac{3.25}{2}-\frac{1}{2}log [2.22]$

$pH = 5.21$

Therefore, The indicator that is best fit for the given titration is Bromocresol Green Color change from pH between 4.0 to 5.6

8 0

3 years ago

35.2 J of heat is

ruslelena [56]

The specific heat : c = 0.306 J/g K

<h3>Further explanation</h3>

Given

Heat = 35.2 J

Mass = 16 g

Temperature difference : 7.2 K =

Required

The specific heat

Solution

Heat can be calculated using the formula:

Q = mc∆T

Q = heat, J

m = mass, g

c = specific heat, joules / g ° C

∆T = temperature difference, ° C / K

Input the value :

c = Q / m.∆T

c = 35.2 / 16 x 7.2

c = 0.306 J/g K

7 0

3 years ago

I need to know what occupied vs full means for chemistry

Anastaziya [24]

You can get the answer on quizlet or google

7 0

3 years ago

What is measured by the reaction rate? the probability that a reaction will occur the speed at which products form the time requ

Cloud [144]

Answer: the speed at which products form

Explanation:

Rate of a reaction is defined as the speed at which a chemical reaction proceeds. It is often expressed in terms of the concentration of a reactant that is consumed in a unit time or the concentration of a product that is formed in a unit of time.

For a general reaction : $A\rightarrow B$

$Rate=-\frac{d[A]}{dt}$

or $Rate=+\frac{d[B]}{dt}$

where d[A] = change in concentration of reactant A

d[B] = change in concentration of product B

dt = time interval

5 0

3 years ago