The majority of elements found in the periodic table can be classified as what

If a gas furnace releases 420 kcal of heat energy, what is the energy in kilojoules? (1 cal = 4.184 J)

Igoryamba

Answer:
The furnace releases 1757280 J

Explanation:
We will do the conversion on two steps:
1- convert the kcal to cal
2- convert the cal to J

Step 1: converting kcal to cal
1 kcal is equivalent to 1000 cal. Therefore:
420 kcal is equivalent to 420*1000 = 420000 cal

Step 2: converting cal to J
We are given that:
<span>1 cal = 4.184 J
</span>Therefore:
420000 cal is equivalent to 420000 * 4.184 = 1757280 J

Hope this helps :)

8 0

4 years ago

Determine the pHpH of an HFHF solution of each of the following concentrations. In which cases can you not make the simplifying

PIT_PIT [208]

The question is incomplete, complete question is :

Determine the pH of an HF solution of each of the following concentrations. In which cases can you not make the simplifying assumption that x is small? ( $K_a$ for HF is $6.8\times 10^{-4}$ .)

[HF] = 0.280 M

Express your answer to two decimal places.

Answer:

The pH of an 0.280 M HF solution is 1.87.

Explanation:3

Initial concentration if HF = c = 0.280 M

Dissociation constant of the HF = $K_a=6.8\times 10^{-4}$

$HF\rightleftharpoons H^++F^-$

Initially

c 0 0

At equilibrium :

(c-x) x x

The expression of disassociation constant is given as:

$K_a=\frac{[H^+][F^-]}{[HF]}$

$K_a=\frac{x\times x}{(c-x)}$

$6.8\times 10^{-4}=\frac{x^2}{(0.280 M-x)}$

Solving for x, we get:

x = 0.01346 M

So, the concentration of hydrogen ion at equilibrium is :

$[H^+]=x=0.01346 M$

The pH of the solution is ;

$pH=-\log[H^+]=-\log[0.01346 M]=1.87$

The pH of an 0.280 M HF solution is 1.87.

6 0

3 years ago

The percent of remaining parent isotope in a radioactive decay process is 40 percent. How many half-lives have elapsed since the

muminat

Answer: Between 1 and 2.

Explanation:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

$a=\frac{a_o}{2^n}$ ............(1)

where,

a = amount of reactant left after n-half lives = 40

$a_o$ = Initial amount of the reactant = 100

n = number of half lives

Putting in the values we get:

$40=\frac{100}{2^n}$

$2^n=2.5$

taking log on both sides

$nlog(2)=log(2.5)$

$n=1.32$

Thus half-lives that have elapsed is between 1 and 2

7 0

3 years ago

Where does ATP store its energy?

RSB [31]

Answer:

D. ATP stores energy in its "tail," which is made from three phosphate groups.

Explanation:

ATP = 3 phosphates

ADP= 2 phosphates

AMP= 1 phosphate

4 0

3 years ago

What would happen if hydrogen and nitrogen combine?

Tanzania [10]

<span>At room temperature and atmospheric pressure, nothing happens when the two gasses are mixed. However, at high temperature and pressure (450C, 200atm), in the presence of an iron oxide catalyst, the production of ammonia is thermodynamically advantageous.</span>

5 0

3 years ago