What were the first 5 planets that were observed? Why were those the only ones? Help pls!

How much heat is required to raise the temperature of 670g of water from 25.7"C to 66,0°C? The specific heat

inna [77]

Answer:

Explanation:

q= mc theta

where,

Q = heat gained

m = mass of the substance = 670g

c = heat capacity of water= 4.1 J/g°C

theta =Change in temperature=( 66-25.7)

Now put all the given values in the above formula, we get the amount of heat needed.

q= mctheta

q=670*4.1*(66-25.7)

=670*4.1*40.3

=110704.1

8 0

3 years ago

What is the pH of a mixture of 0.042 M NaH2PO4 and 0.058 M Na2HPO4? Hint: The pKa of phosphate is 6.86.

AlekseyPX

Answer:

The pH value of the mixture will be 7.00

Explanation:

Mono and disodium hydrogen phosphate mixture act as a buffer to maintain pH value around 7. Henderson–Hasselbalch equation is used to determine the pH value of a buffer mixture, which is mathematically expressed as,

$pH=pK_{a} + log(\frac{[Base]}{[Acid]})$

According to the given conditions, the equation will become as follow

$pH=pK_{a} + log(\frac{[Na_{2}HPO_{4} ]}{[NaH_{2}PO_{4}]})$

The base and acid are assigned by observing the pKa values of both the compounds; smaller value means more acidic. NaH₂PO₄ has a pKa value of 6.86, while Na₂HPO₄ has a pKa value of 12.32 (not given, but it's a constant). Another more easy way is to the count the acidic hydrogen in the molecular formula; the compound with more acidic hydrogens will be assigned acidic and vice versa.

Placing all the given data we obtain,

$pH=6.86 + log(\frac{0.058}{0.042})$

$pH=7.00$

5 0

3 years ago

A gas tank contains 3 gases (N2, O2, and CO2). The total pressure of the gases is 825mmHg. If Pco2 = 125mmHg and Po2= 350mmHg, w

DedPeter [7]

Answer:

350mmHg

Explanation:

Use Dalton law

Total=P gas 1+p gas 2+ P gas 3

825=P1+350+125

825=P1+475

825-475= P1

P1= 350 mm Hg

3 0

2 years ago

_____ The primary function of molecular membranes is the transport of ions and molecules into and out of cells. The movement of

ale4655 [162]

<h2>Active Transport </h2>

Explanation:

A cell uses energy for the movement of substances against a concentration gradient or an electrochemical gradient that maintains a balanced concentration of ions and molecules in living cells.
This transport of substances is known as Active transport mechanisms which are the basic function of the cell membranes.
The energy used is in the form of ATP.
Active transport occurs when there is a difference in the concentration of particles on both sides.

5 0

3 years ago

Where does an eagle get the energy it needs to grow and to fly?

NeTakaya

An eagle gets energy from food. When the eagle eats food it gives them energy to be active just like us humans

7 0

2 years ago

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