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3 years ago

The first method of determining the chemical composition of substances in space was to

Chemistry

2 answers:

Bas_tet [7]3 years ago

7 0

this varified answer is incorrect. the answer is analyze starlight transmitted to Earth

ehidna [41]3 years ago

5 0

The first method to determine the chemical composition of a substance in space was using light. By determining red shift in the observed spectrum of light they could determine the elements they were observing. Different elements change the way light behaves and from this scientists can determine the makeup of things such as stars and nebulas.

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Ca3(PO4)2 + H2SO4 → CaSO4 + H3PO4 Balance this reaction if necessary

devlian [24]

Ca3(PO4)2 + 3 H2SO4 = 3 CaSO4 + 2 H3PO4
Reaction type: double replacement

7 0

3 years ago

Read 2 more answers

HELP!

katovenus [111]

Answer:

116.88 g

Explanation:

Step 1: Write the balanced equation for the synthesis of NaCl

Na + 1/2 Cl₂ ⇒ NaCl

Step 2: Calculate the moles corresponding to 45.978 g of Na

The molar mass of Na is 22.990 g/mol.

45.978 g × 1 mol/22.990 g = 1.9999 mol

Step 3: Calculate the number of moles of NaCl formed from 1.9999 moles of Na

The molar ratio of Na to NaCl is 1:1. The moles of NaCl formed are 1/1 × 1.9999 mol = 1.9999 mol.

Step 4: Calculate the mass corresponding to 1.9999 moles of NaCl

The molar mass of NaCl is 58.443 g/mol.

1.9999 mol × 58.443 g/mol = 116.88 g

3 0

3 years ago

The pH of a 0.78M solution of 4-pyridinecarboxylic acid HC6H4NO2is measured to be 2.53.Calculate the acid dissociation constant

nika2105 [10]

Answer : The value of acid dissociation constant is, $1.1\times 10^{-5}$

Solution : Given,

Concentration pyridinecarboxylic acid = 0.78 M

pH = 2.53

First we have to calculate the hydrogen ion concentration.

$pH=-\log [H^+]$

$2.53=-\log [H^+]$

$[H^+]=2.95\times 106{-3}M$

Now we have to calculate the acid dissociation constant.

The equilibrium reaction for dissociation of (weak acid) is,

$HC_6H_4NO_2\rightleftharpoons C_6H_4NO_2^-+H^+$

initially conc. 0.78 0 0

At eqm. (0.78-x) x x

The expression of acid dissociation constant for acid is:

$k_a=\frac{[C_6H_4NO_2^-][H^+]}{[C_6H_4NO_2]}$

As, $[H^+]=[C_6H_4NO_2^-]=x$

So, $x=2.95\times 106{-3}M$

Now put all the given values in this formula ,we get:

$k_a=\frac{(x)\times (x)}{(0.78-x)}$

$k_a=\frac{(2.95\times 106{-3})\times (2.95\times 106{-3})}{(0.78-2.95\times 106{-3})}$

$K_a=1.1\times 10^{-5}$

Therefore, the value of acid dissociation constant is, $1.1\times 10^{-5}$

7 0

4 years ago

How does a physical change obey the law of conservation of mass?

iren2701 [21]

Let's consider water.
Regardless of what form it turns into, the mass should remain the same.
It's the same H20.
Add some heat and it becomes water vapor,
cool it down a bit and it becomes ice.
if you make it just right, it becomes water again.

A chemical change would involve the one or more element(s) changing into a different solution all together.
It cannot be reversed unless you use electrolysis or some other method.

5 0

3 years ago

The following pairs of soluble solutions can be mixed. In some cases, this leads to the formation of an insoluble precipitate. D

Gekata [30.6K]

Answer:

See explanation

Explanation:

Let us see what happens when each solution is mixed;

a) AlCl3(aq) + K3PO4(aq) ------> 3KCl(aq) + AlPO4(s)

A precipitate is formed here

b) RbCO3(aq) + NaCl(aq) -------> This is an impossible reaction hence no solid precipitate is formed here

c) MnCl2(aq) + Na2CO3(aq) → 2NaCl(aq) + MnCO3(s)

A precipitate is formed.

d) K2S(aq) + 2NH4Cl(aq) ------> 2KCl(aq) + (NH4)2S(aq)

No solid precipitate is formed

e) CaCl2(aq) + (NH4)2CO3(aq) → CaCO3(s) + 2NH4Cl(aq)

A solid precipitate is formed

3 0

3 years ago