For each of the molecules determine if they have the following center of symmetry, the axis of symmetry and plane of symmetry

2) In a calorimetry experiment, 70.0 g of a substance was heated to

Aloiza [94]

The temperature at thermal equilibrium : 16.1 °C

<h3>Further explanation</h3>

Q absorbed = Q released

Heat can be formulated :

Q = m.c.Δt

c= specific heat, J/g°C

Δt = temperature different, C°

m= mass, g

Q water=Q substance

$\tt 3500\times 4.18\times (t_2-15)=70\times 0.89\times (270-t_2)\\\\14630(t_2-15)=62.3(270-t_2)\\\\14630t_2-219450=16821-62.3t_2\\\\14692.3t_2=236271\\\\t_2=16.1^oC$

8 0

3 years ago

What's the answer to this and why? need a answer asap

ioda

Answer:

Aluminum

Explanation:

Because there's no other element that has this exact electron configuration

4 0

3 years ago

Consider a mixture of NaCl and NaNO3 that is 31.8% Na by mass. Calculate the percentage by mass of NaCl in the mixture.

lutik1710 [3]

<u>Answer:</u> The percentage by mass of NaCl in the mixture is 38.5 %

<u>Explanation:</u>

To calculate the mass percentage of element in compound, we use the equation:

$\text{Mass percent of element}=\frac{\text{Mass of element}}{\text{Mass of compound}}\times 100$ .......(1)

<u>For NaCl:</u>

Mass of sodium element = 23 g

Mass of NaCl = 58.5 g

Putting values in equation 1, we get:

$\text{Mass percent of sodium element}=\frac{23g}{58.5g}\times 100=39.32\%$

Mass fraction of sodium metal in NaCl = 0.3932

<u>For $NaNO_3$ :</u>

Mass of sodium element = 23 g

Mass of $NaNO_3$ = 85 g

Putting values in equation 1, we get:

$\text{Mass percent of sodium element}=\frac{23g}{85g}\times 100=27.1\%$

Mass fraction of sodium metal in sodium nitrate = 0.271

Let us assume the mass fraction of NaCl in the mixture is 'x'

So, the mass fraction of $NaNO_3$ in the mixture will be '(1-x)'

We are given:

Percent by mass of Na in the mixture = 31.8 %

Mass fraction of Na in the mixture = 0.318

Evaluating the mass fraction of NaCl in the mixture:

$[(x\times 0.3932)+((1-x)\times 0.271)]=0.318$

x = 0.385

Percent by mass of NaCl in the mixture will be = $(0.385\times 100)=38.5\%$

Hence, the percentage by mass of NaCl in the mixture is 38.5 %

4 0

3 years ago

Formula units in 0.0300 moles of cacl2

spin [16.1K]

Answer:

no of formula unit = $0.03\times 6.023\times 10^{23}=1.8\times 10^{22}$

Explanation:

atomic mass of CaCl2 = 40 + 2×35.5 = 111 g.

no of formula unit = no of moles × Avagadro number

= $0.03\times 6.023\times 10^{23}=1.8\times 10^{22}$

3 0

4 years ago

It is believed that two C-12 nuclei can react in the core of a supergiant star to form Na-23 and H-1. Calculate the energy relea

Leno4ka [110]

Answer:

c. 2.16 × 10^8 kJ

Explanation:

In the given question, 2 C-12 nuclei were used for the reaction and the mass of C-12 is 12.0000 amu. Therefore, for 2 C-12 nuclei, the mass is 2*12.0000 = 24.0000 amu.

In addition, a Na-23 and a H-1 were formed in the process. The combined mass of the products is 22.989767+1.007825 = 23.997592 amu

The mass of the reactant is different from the mass of the products. The difference = 24.0000 amu - 23.997592 amu = 0.002408 amu.

Theoretically, 1 amu = 1.66054*10^-27 kg

Thus, 0.002408 amu = 0.002408*1.66054*10^-27 kg = 3.99858*10^-30 kg

This mass difference is converted to energy and its value can be calculated using:

E = mc^2 = 3.99858*10^-30 *(299792458)^2 = 3.59374*10^-13 J

Furthermore, 1 mole of hydrogen nuclei contains 6.022*10^23 particles. Thus, we have:

E = 3.59374*10^-13 * 6.022*10^23 = 2.164*10^11 J = 2.164*10^8 kJ

4 0

4 years ago