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just olya [345]
4 years ago
13

Does endothermic means to lose energy?

Chemistry
2 answers:
pentagon [3]4 years ago
7 0
It means to release energy
Molodets [167]4 years ago
5 0
Я проснулся, Крис свежее, я мужчина
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How did thomsons experiment changes daltons atomic model
podryga [215]

Thomson's experiments with cathode ray tubes helped him to discover the electron (which Dalton did not know about). Dalton thought that atoms were indivisible particles, and Thomson's discovery of the electron proved the existence of subatomic particles.

5 0
4 years ago
Read 2 more answers
How many molecules of sodium oxide will be created if 187 grams of oxygen reacts with excess sodium? 4na o2 -> 2na2o
Leona [35]

Molecules of sodium oxide will be created if 187 grams of oxygen reacts with excess sodium will be 7.04 × 10 ²⁴ molecules.

Sodium oxide is Na₂O which is formed due to the reaction of sodium and oxygen.

Given,

Balanced chemical equation is :

         4 Na(s) + O₂ (g) → 2Na₂O (s)

Now, the Mole ratio of O₂ and Na₂O is 1 mol O₂: 2 mol Na₂O

Molar mass O₂ = 32.00 g/mol

Now, let's find out the Number of moles of O₂ present in 187 grams of oxygen,

Number of moles of O₂ = Given mass in grams / molar mass of O₂

Number of moles of O₂ = 187 g / 32.00 g/mol

Number of moles of O₂ = 5.844 mol

Since, we know the Proportion is 1 mol O₂ : 2 mol Na₂O

Now, Number of moles of Na₂O required is,

2 mol Na₂O / 1 mol O₂ = 5.844 mol O₂ / x

x = 5.844 mol O₂ (2 mol Na₂O / 1 mol O₂)

x = 11.688 mol Na₂O

To calculate the Number of molecules of sodium oxide,

Number of molecules = Number of moles × Avogadro's number

Number of molecules = 11.688 mol × 6.022 × 10²³ molecules/mol =

Number of molecules = 7.04 × 10 ²⁴ molecules

Hence, the Number of molecules of sodium oxide required is 7.04 × 10²⁴ molecules.                          

Learn more about Sodium oxide here,

brainly.com/question/12623179

#SPJ4

3 0
2 years ago
Need help. Djjddhdhdbdhs
Maurinko [17]
It sound like it is D, but i don’t asure you anything.
7 0
3 years ago
Read 2 more answers
I have no idea what to do or how to do it?
sukhopar [10]
10) In order to find the conjugate acid of a chemical you just add a hydrogen to the chemical.  
examples:  the conjugate acid of Cl⁻ is HCl, the conjugate acid of PO₄³⁻ is HPO₄²⁻, the conjugate acid of NH₃ is NH₄⁺, the conjugate acid of HCO₃⁻ is H₂CO₃, and the conjugate acid of H₂O is H₃O⁺
To find the conjugate base of a chemical you just reverse that process (take away a hydrogen).
examples: the conjugate base of H₂SO₄ is HSO₄⁻, the conjugate base of CH₃COOH is CH₃COO⁻, the conjugate base of H₃PO₄ is H₂PO₄⁻, and the conjugate base of H₂O is OH⁻.

When you identify conjugate acids and bases in a reaction you look to see what lost a proton and what gained a proton.  The chemical that gave up the proton acted as an acid and produced a conjugate base while the chemical that accepted a proton produced a conjugate acid.
Example: HCl+NaOH⇒NaCl+H₂O  The acid is HCl and its conjugate base is Cl⁻ while NaOH was the base and H₂O is the conjugate acid.  (you can ignore the sodium since it is a spectator ion).

 11) When completing acid base reactions, need to identify the acid and the base since the acid will give a proton the base creating a conjugate base of the acid and conjugate acid of the base. (You need to balance the equation after you determine what the products will be)
example: H₂SO₄+2NaOH⇒Na₂SO₄+2H₂O  (SO₄²⁻ is the conjugate base of HSO₄⁻ which is the conjugate base of H₂SO₄.  HSO⁻ is created with the first NaOH molecule and then SO₄⁻ is created with the second NaOH.)

12) All acid base reaction form a salt consisting of the cation from the base and anion from the acid.  
examples:  NaCl could have come from NaOH reacting with HCl.  K₃PO₄ could have come from KOH and H₃PO₄.

13) I don't really know how you are supposed to solve it with out knowing the Ka value of H₂S.  H₂S is a weak acid and therefore will not dissociate completely in water so the only way of being able to find the concentration of H⁺ ions that dissociate is knowing the Ka value of H₂S and using ice tables.  (Ka=[H⁺][A⁻]/[HA] and is basically the equilibrium constant for the acid when put into water where A⁻ is the conjugate base and HA is the acid).

14) Ca(OH)₂ is a strong base and will therefore dissociate completely in water.  That means that when you find the concentration of OH⁻ in solution you can multiply that by the volume of the solution (in liters) to find the number of moles of OH⁻.  Then you can divide that by 2 to find the number of moles of Ca(OH)₂ needed.  pOH=14-pH which means that pOH=4.2.  [OH⁻]=10^-pOH which means [OH⁻]=6.3x10^-5 M.  6.3x10^-5Mx3.00L=1.89x10^-4mol OH⁻ which means that (1.89x10^-4)/2=9.46x10^-5mol Ca(OH)₂.

I hope this helps.  Let me know if anything is unclear.
6 0
4 years ago
Mass of a man is 80kg. Assuming that a human body Contains 70% water, calculate the total no. of water molecules present in the
sergejj [24]

Answer:

Given,

Maas of the man = 80 kg

Percentage of water molecules it contains = 70%

Therefore,

Total no. of water molecules mass present in our human body

= 70  \: percent\: of \: 80kg

=  \frac{70}{100}  \times 80

=  \frac{70}{5}  \times  \frac{4}{1}

= 14 \times 4

= 56

Answer - The total number of water molecules present in our body is 56 kg.

Hope it helps you!!

#IndianMurga

6 0
3 years ago
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